Corticosteroid Treatment Impairs Epithelial Regeneration, Limiting Intestinal Recovery in Experimental Graft Vs Host Disease

Abstract Corticosteroids (CS) represent first-line treatment for gastrointestinal graft vs host disease (GI GVHD), and CS failure is associated with severe morbidity and mortality. While the immune system is the intended target of CS treatment, the glucocorticoid receptor (GR) is widely expressed, and there is limited understanding of the direct effects of CS on intestinal epithelium following immune-mediated damage. We thus investigated how CS treatment could impact intestinal homeostasis and regeneration following experimental bone marrow transplantation (BMT). In healthy C57BL/6 (B6) mice, in vivo administration of clinically relevant CS doses reduced Ki67 + epithelial proliferation in the ileum (p<0.001; Fig. 1A) without inducing crypt loss or overt pathology. Given the numerous potential effects of systemic administration, we next utilized ex vivo small intestine (SI) organoid cultures to explore direct effects of CS on murine and human epithelium. Assessing a variety of clinically relevant CS agents, we found that methylprednisolone (MP), dexamethasone, and budesonide all decreased murine organoid size without affecting organoid number (p<0.05; only MP shown; Fig. 1B). We also identified that GR-deficient (Nr3c1 -/-) organoids were significantly resistant to growth inhibition by MP (p<0.05), indicating a direct GR-mediated effect of CS on intestinal epithelium leading to reduced growth. Furthermore, MP treatment significantly decreased the size of human organoids generated from primary duodenal tissue without affecting organoid numbers (p<0.001). Organoid culture models were thus highly consistent with the findings from in vivo CS treatment. We next investigated CS effects on epithelial cells during immune-mediated damage. Pre-treatment of mice with 2 mg/kg MP x 7 days in vivo prior to crypt harvest and organoid culture increased organoid sensitivity to T-cell-mediating killing ex vivo (p<0.05). Additionally, modeling steroid-refractory disease, GR-deficient (Nr3c1 -/-) T cells mediated greater killing of SI organoids if co-cultures were performed in the presence of MP (p<0.01). We next investigated CS-mediated effects on epithelial damage in vivo, treating with MP x 7 days starting on day 7 after MHC-mismatched BMT, once GVHD had already been established. Vehicle-treated mice demonstrated GVHD-associated T cell activation, lymphocytic tissue infiltration, and ileal crypt loss compared to BM only controls, as well as increased height and Ki67 + cell frequency in residual crypts reflecting damage-induced regeneration (p<0.001, Fig. 2A-C). Modeling steroid-refractory disease, systemic CS treatment failed to reduce T cell activation or lymphocytic infiltration. However, MP treatment appeared to attenuate regeneration and worsen intestinal pathology, as evidenced by exacerbated crypt loss in association with reduced crypt height and Ki67 + cell frequency (p<0.01; Fig. 2A-C). Despite potential harmful side effects, CS are frequently necessary for treatment of clinical GVHD. We hypothesized that CS-mediated epithelial suppression could be mitigated by concurrent administration of agents capable of inducing tissue regeneration. Interleukin-(IL)-22 has been shown to promote epithelial proliferation and recovery following GI damage. We thus investigated whether IL-22 treatment could counterbalance CS-induced impairment of epithelial recovery in GVHD. Indeed, addition of IL-22 to MP-treated organoids promoted organoid growth without inducing toxicity/organoid loss in both murine and human SI organoid cultures (p<0.001; Fig. 3A and B). Moreover, IL-22 administration in vivo with F-652, a clinical grade recombinant human IL-22 dimer, reversed MP-mediated crypt loss and reduction of crypt height and Ki67 + cell frequency in mice with GVHD (p<0.001; Fig. 3C). In summary, these findings indicate that CS treatment can suppress epithelial proliferation in the intestines and exacerbate GI damage if it fails to control the pathologic immune response. However, deleterious CS side effects can be counterbalanced by promotion of epithelial regeneration, providing rationale for combining immunosuppression with tissue-supporting therapeutics such as IL-22 to optimize intestinal recovery in GVHD. Figure 1 Figure 1. Disclosures Blazar: Magenta Therapeutics: Membership on an entity's Board of Directors or advisory committees; BlueRock Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Rheos Medicines: Research Funding; Equilibre Pharmaceuticals Corp: Research Funding; Carisma Therapeutics, Inc: Research Funding; Tmunity Therapeutics: Other: Co-founder. Hanash: Evive Biotech: Ended employment in the past 24 months.

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Clinical Efficacy of Anti-CD22 Chimeric Antigen Receptor T Cells for B-Cell Acute Lymphoblastic Leukemia Is Correlated with the Length of the Scfv Linker and Can be Predicted Using Xenograft Models

Blood ◽

10.1182/blood.v130.suppl_1.807.807 ◽

2017 ◽

Vol 130 (Suppl_1) ◽

pp. 807-807

Author(s):

Marco Ruella ◽

Shannon L Maude ◽

Boris Engels ◽

David M. Barrett ◽

Noelle Frey ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

T Cell Activation ◽

Research Funding ◽

Cell Activation ◽

Lymphoblastic Leukemia ◽

Advisory Committees ◽

Xenograft Models

Abstract Introduction. Anti-CD19 chimeric antigen receptor T cells (CART19 or CTL019) have shown impressive clinical activity in B-cell acute lymphoblastic leukemia (B-ALL) and are poised to receive FDA approval. However, some patients relapse after losing CD19 expression. Since CD22 remains highly expressed in relapsed/refractory (r/r) B-ALL even in these patients, anti-CD22 CART (CART22) have been developed. The National Cancer Institute (NCI) reported 4/9 complete remission (CR) in patients receiving CART22, with 100% CR at the highest T cell dose (NCT02315612)(S hah NN, ASH 2016 #650). Patients and Methods. We generated a second-generation CAR22 differing from that used by the NCI only by the use of a longer linker [4x(GGGGS); LL vs. 1x(GGGGS); SL] between the light and heavy chains of the scFv (Fig. 1 A). This construct was tested in two pilot clinical trials in adults (NCT02588456)and children with r/r-ALL (NCT02650414). CART22 cells were generated using lentiviral transduction as in our previous studies. The protocol-specified CART22 dose was 2x106-1x107 cells/kg for pediatric patients <50kg and 1-5x108 for pediatric patients ≥50kg and adult patients,. infused after lymphodepleting chemotherapy. Patient characteristics are described in Table 1. For the adult trial, 5 patients were screened, 4 enrolled (1 patient withdrew consent) and 3 infused (1 manufacturing failure). For the pediatric trial, 9 patients were screened, 8 enrolled (1 screen failure) and 6 infused (two patients were not infused for disease progression). For the preclinical studies, we generated CART22LL and CART22SL and tested them in vivo using xenograft models. NOD-SCID gamma chain deficient (NSG) mice were engrafted with either a luciferase+ standard B-ALL cell line (NALM6) or primary B-ALL cells obtained from a patient relapsing after CART19 (CHP110R). We also used 2-photon imaging to study the in vivo behavior and immune synapse formation and flow cytometry to asses T cell activation. Results. CART22 cells were successfully manufactured for 10/12 patients. In the adult cohort 3/3 patients developed CRS (gr.1-3) and no neurotoxicity was observed; in the pediatric cohort out of 5 evaluable patients (1 discontinued for lineage switch to AML on pre-infusion marrow), 3/5 developed cytokine-release syndrome (CRS) (all grade 2) and 1 patient had encephalopathy (gr.1). CART22 cells expanded in the PB with median peak of 1977 (18-40314) copies/ug DNA at day 11-18. Interestingly, in an adult patient who had previously received CART19 a second CART19 re-expansion was observed following CART22 expansion (Fig 1 B). At day 28, in the adult cohort the patient who was infused in morphologic CR remained in CR, while the other 2 had no response (NR); in the pediatric cohort 2/5 patients were in CR, 1 in partial remission (PR) that then converted to CR with incomplete recovery at 2 months, and 2 NR. No CD22-negative leukemia progression was observed. Since our results with a long linker appeared inferior compared to the previously reported CART22 trial (short linker), we performed a direct comparison of the 2 different CAR22 constructs. In xenograft models, CART22SL significantly outperformed CART22LL (Fi 1 C) with improved overall survival. Moreover, CART22SL showed higher in vivo proliferation at day 17 (Fig 1 D). Mechanistically, intravital 2-photon imaging showed that CART22SL established more protracted T cell:leukemia interactions than did CART22LL, suggesting the establishment of productive synapses (Fig 1 E). Moreover, in vivo at 24 hrs higher T cell activation (CD69, PD-1) was observed in CART22SL from the BM of NALM-6-bearing mice. Conclusions. Here we report the results of two pilot clinical trials evaluating the safety and feasibility of CART22 therapy for r/r B-ALL. Although feasible and with manageable toxicity CART22LL led to modest clinical responses. Preclinical evaluation allowed us to conclude that shortening the linker by 15 amino acids significantly increases the anti-leukemia activity of CART22, possibly by leading to more effective interactions between T cells and their targets. Finally, with the caveats of cross-trial comparison, our data suggest that xenograft models can predict the clinical efficacy of CART products and validate the use of in vivo models for lead candidate selection Disclosures Ruella: Novartis: Patents & Royalties, Research Funding. Maude: Novartis Pharmaceuticals: Consultancy, Other: Medical Advisory Boards. Engels: Novartis: Employment. Frey: Novartis: Research Funding. Lacey: Novartis: Research Funding; Genentech: Honoraria. Melenhorst: Novartis: Research Funding. Brogdon: Novartis: Employment. Young: Novartis: Research Funding. Porter: Incyte: Honoraria; Novartis: Honoraria, Patents & Royalties, Research Funding; Immunovative Therapies: Other: Member DSMB; Genentech/Roche: Employment, Other: Family member employment, stock ownship - family member; Servier: Honoraria, Other: Travel reimbursement. June: WIRB/Copernicus Group: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celldex: Honoraria, Membership on an entity's Board of Directors or advisory committees; Immune Design: Equity Ownership, Membership on an entity's Board of Directors or advisory committees; Novartis: Patents & Royalties, Research Funding; Tmunity Therapeutics: Equity Ownership, Research Funding. Grupp: Jazz Pharmaceuticals: Consultancy; Novartis Pharmaceuticals Corporation: Consultancy, Other: grant; University of Pennsylvania: Patents & Royalties; Adaptimmune: Consultancy. Gill: Novartis: Patents & Royalties, Research Funding.

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Tumor masses support naive T cell infiltration, activation, and differentiation into effectors

Journal of Experimental Medicine ◽

10.1084/jem.20092454 ◽

2010 ◽

Vol 207 (8) ◽

pp. 1791-1804 ◽

Cited By ~ 134

Author(s):

Elizabeth D. Thompson ◽

Hilda L. Enriquez ◽

Yang-Xin Fu ◽

Victor H. Engelhard

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Cd8 T Cells ◽

Adoptive Transfer ◽

Cell Activation ◽

Ex Vivo ◽

Tumor Infiltrating Lymphocytes ◽

T Cell Infiltration

Studies of T cell responses to tumors have focused on the draining lymph node (LN) as the site of activation. We examined the tumor mass as a potential site of activation after adoptive transfer of naive tumor-specific CD8 T cells. Activated CD8 T cells were present in tumors within 24 h of adoptive transfer and proliferation of these cells was also evident 4–5 d later in mice treated with FTY720 to prevent infiltration of cells activated in LNs. To confirm that activation of these T cells occurred in the tumor and not the tumor-draining LNs, we used mice lacking LNs. Activated and proliferating tumor-infiltrating lymphocytes were evident in these mice 24 h and 4 d after naive cell transfer. T cells activated within tumors acquired effector function that was evident both ex vivo and in vivo. Both cross-presenting antigen presenting cells within the tumor and tumor cells directly presenting antigen activated these functional CD8 effectors. We conclude that tumors support the infiltration, activation, and effector differentiation of naive CD8 T cells, despite the presence of immunosuppressive mechanisms. Thus, targeting of T cell activation to tumors may present a tool in the development of cancer immunotherapy.

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T-cell redirected killing and cure of pancreatic and gastric cancer xenografts by targeting Trop-2.

Journal of Clinical Oncology ◽

10.1200/jco.2015.33.3_suppl.262 ◽

2015 ◽

Vol 33 (3_suppl) ◽

pp. 262-262

Author(s):

David M. Goldenberg ◽

Edmund A. Rossi ◽

Diane L Rossi ◽

Thomas M. Cardillo ◽

Chien-Hsing Chang

Keyword(s):

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Ex Vivo ◽

Control Group ◽

Calcium Signal ◽

Target Cells ◽

Normal Tissues

262 Background: Trop-2 [also called tumor-associated calcium signal transducer 2 (TACSTD2), EGP-1 (epithelial glycoprotein-1), GA733-1, or M1S1]is a 35 kDa transmembrane glycoprotein that is overexpressed relative to normal tissues in a variety of human cancers, including pancreatic and gastric carcinomas, where increased expression correlates with poor prognosis. Trop-2 appears to be more tumor-specific than the related molecule, EpCAM (Trop-1). MT110, the EpCAM antibody x CD3 bispecific T-cell engager (BiTE), is currently undergoing a Phase I study in various solid tumors, including lung, gastric, colorectal, breast, prostate, and ovarian cancers. We produced a similar T-cell redirecting bispecific tandem scFv, E1-3, using the variable domains of hRS7 (humanized anti-Trop-2 mAb) and Okt-3 (anti-CD3 mAb). Methods: T-cell activation, cytokine induction and cytotoxicity were evaluated ex vivo using PBMCs or purified T cells with human pancreatic (Capan-1 and BxPC3) and gastric (NCI-N87) cancer cell lines as target cells. In vivo activity was assayed with NCI-N87 xenografts that were inoculated s.c. in a mixture with twice the number of human PBMCs and matrigel. Results: In the presence of target cells and PBMCs, E1-3 potently induced T-cell activation, proliferation, and dose-dependent cytokine production of IL-2 (>2 ng/mL), IL-6 (>1 ng/mL), IL-10 (>7 ng/mL), TNF-α (>1 ng/mL) and IFN-γ (>50 ng/mL). In vitro, E1-3 mediated a highly potent T-cell lysis of BxPC3 [IC50=0.09(±0.04) pM], Capan-1 [IC50=1.2(±1.1) pM] and NCI-N87 [IC50=1.2(±1.2) pM] target cells. In vivo, two 50-µg doses of E1-3 given three days apart cured all of the mice (N=8) bearing NCI-N87 xenografts (P=0.0005; Log-Rank). Tumors in the control group (PBMCs only) reached the endpoint (TV>1 cm3) with a median of 39.5 days. All mice remained tumor-free in the E1-3 group at 78 days. Conclusions: Trop-2 is an attractive target for T-cell-mediated killing of pancreatic, gastric and other epithelial cancers.

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The Innate Immune Sensor Sting Promotes Donor CD8+ T Cell Activation and Recipient APC Death Early after Preclinical Allogeneic Hematopoietic Stem Cell Transplantation

Blood ◽

10.1182/blood-2019-130197 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 3202-3202

Author(s):

Cameron S. Bader ◽

Henry Barreras ◽

Casey O. Lightbourn ◽

Sabrina N. Copsel ◽

Dietlinde Wolf ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Board Of Directors ◽

T Cell Activation ◽

Cd8 T Cells ◽

Research Funding ◽

Cell Activation ◽

Cd8 T Cell ◽

Advisory Committees ◽

Hematopoietic Stem

Graft-versus-host disease (GVHD) remains a significant cause of morbidity and mortality in patients receiving allogeneic hematopoietic stem cell transplants (aHSCTs). Pre-HSCT conditioning typically consists of irradiation and drug administration resulting in the death of rapidly dividing cells and release of endogenous danger signals. These molecules drive the activation of antigen presenting cells (APCs) and the differentiation of allo-reactive donor T cells, leading to damage of particular host tissues characteristic of GVHD. Cell death following conditioning has promoted the hypothesis that sensors of cytoplasmic DNA damage in GVHD target tissues contribute to pro-inflammatory cytokine production. We identified a role for Stimulator of Interferon Genes (STING), an innate immune sensor, in GVHD using pre-clinical MHC-matched unrelated donor (MUD) aHSCT models. Here we show that STING rapidly promotes donor CD8+ T cell activation and recipient APC death early after aHSCT. To assess STING involvement immediately post-HSCT, cytokine mRNA expression was examined 48 hrs after transplant of MUD C3H.SW bone marrow (BM) + T cells into irradiated B6 wildtype (WT) or STING-/- recipients. Colon tissue from STING-/- recipients had >2x reduction in IFNβ, TNFα and IL-6 mRNA vs WT. MUD STING-/- HSCT recipients also experienced decreased weight loss, GVHD scores and skin pathology 6 wks post-HSCT vs WT. Double chimerism studies showed that the absence of STING in non-hematopoietic cells was responsible for GVHD amelioration. Conversely, a single dose of the highly specific STING agonist DMXAA given in vivo increased IFNβ, TNFα and IL-6 mRNA expression in WT, but not STING-/-, colon tissue 48 hrs after transplant and increased GVHD scores and lethality post-HSCT. Post-transplant cytoxan treatment abolished the ability of DMXAA to augment GVHD, supporting the notion that STING signaling increases donor T cell activation during aHSCT. To evaluate the potential impact of STING in the clinical setting, we transplanted C3H.SW BM + T cells into mice homozygous for a murine homologue of a human allele associated with diminished STING activity (STINGHAQ/HAQ) and found that these mice also exhibited diminished GVHD. Interestingly, our findings that STING deficiency ameliorates GVHD in MUD aHSCT contrasts to reported observations that STING deficiency can exacerbate GVHD after MHC-mismatched (MMUD) aHSCT (Fischer J, et al, Sci. Transl. Med. 2017). Since CD4+ and CD8+ T cells are central in MMUD and MUD GVHD, respectively, we hypothesized that STING's effect on the predominant T cell subset in each model may explain these seemingly paradoxical results in STING-/- vs WT recipients. Therefore, we transplanted MMUD BALB/c BM + CD8+ T cells into B6-WT and STING-/- mice and found that - in contrast to MMUD recipients of combined CD4+ and CD8+ T cells - STING-/- recipients developed lower GVHD clinical scores, reduced skin pathology and had lower frequencies of activated T cells 8 wks post-HSCT vs WT, supporting a role for STING in the promotion of CD8+ T cell-mediated GVHD. Next, we investigated if recipient APCs played a role in STING's enhancement of CD8+ T cell-mediatedGVHD. We found that STING-/- mice had greater frequencies and numbers of recipient splenic CD11b+CD11c+ APCs 1 day after MMUD B6 into BALB/c aHSCT (Fig. A). BALB/c-STING-/- APCs also expressed reduced MHC class I protein levels (Fig. B). Moreover, STING-/- recipient spleens contained lower numbers of donor CD8+ T cells producing IFNγ and TNFα (Fig. C). These data support the hypothesis that STING contributes to early activation of donor CD8+ T cells and elimination of recipient APCs. Next, to identify if the loss of host MHC II+ APCs affected subsequent donor CD4+ T cell activation, B6-Nur77GFP transgenic donor T cells were used to explicitly monitor T cell receptor signaling. Consistent with increased numbers of host MHC II+ APCs in the spleens of STING-/- recipients 1 day post-aHSCT, we found greater frequencies and numbers of donor Nur77GFP CD4+ T cells expressing GFP, CD69 and IFNγ in STING-/- spleens 6 days after transplant (Fig. D). In summary, our studies demonstrate that STING plays an important role in regulating aHSCT and provide one potential mechanism by which STING could promote CD8+ T cell-mediated GVHD yet diminish CD4+-mediated GVHD. Overall, our studies suggest this pathway can provide a target for new therapeutic strategies to ameliorate GVHD. Disclosures Blazar: BlueRock Therapeutics: Membership on an entity's Board of Directors or advisory committees; Childrens' Cancer Research Fund: Research Funding; KidsFirst Fund: Research Funding; Tmunity: Other: Co-Founder; Kamon Pharmaceuticals, Inc: Membership on an entity's Board of Directors or advisory committees; Regeneron Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Five Prime Therapeutics Inc: Co-Founder, Membership on an entity's Board of Directors or advisory committees; Magenta Therapeutics and BlueRock Therapeuetics: Membership on an entity's Board of Directors or advisory committees; Fate Therapeutics, Inc.: Research Funding; RXi Pharmaceuticals: Research Funding; Alpine Immune Sciences, Inc.: Research Funding; Abbvie Inc: Research Funding; Leukemia and Lymphoma Society: Research Funding. Levy:Heat Biologics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pelican Therapeutics: Consultancy, Research Funding.

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886 Targeting VSIG4, a novel macrophage checkpoint, repolarizes suppressive macrophages which induces an inflammatory response in primary cell in vitro assays and fresh human tumor cultures

Journal for ImmunoTherapy of Cancer ◽

10.1136/jitc-2021-sitc2021.886 ◽

2021 ◽

Vol 9 (Suppl 3) ◽

pp. A928-A928

Author(s):

Steve Sazinsky ◽

Phuong Nguyen ◽

Mohammad Zafari ◽

Ryan Phennicie ◽

Joe Wahle ◽

...

Keyword(s):

Lung Cancer ◽

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Immune Cell ◽

Ex Vivo ◽

Syngeneic Mouse ◽

Pathogen Clearance

BackgroundVSIG4 (V-set immunoglobulin-domain-containing 4) is a B7 family related protein with known roles as a complement receptor involved in pathogen clearance as well as a negative regulator of T cell activation by an undetermined mechanism.1–3 VSIG4 is expressed in tumor associated macrophages (TAMs) with exquisite specificity. In cancer, increased expression of VSIG4 has been associated with worse survival in multiple indications, including non-small cell lung cancer, multiple myeloma, ovarian cancer, and glioma, suggesting an important role in tumor immune evasion.3–6 Based upon computational analysis of transcript data across thousands of primary cancer and normal tissue samples, we hypothesized that VSIG4 has an important regulatory role in promoting M2-like immune suppressive macrophages in the tumor microenvironment, and that targeting VSIG4 via a monoclonal antibody could relieve VSIG4-mediated macrophage suppression by repolarizing TAMs to an inflammatory phenotype capable of coordinating an anti-tumor immune response.MethodsThe ability of anti-VSIG4 antibodies to repolarize M2-like macrophages and induce T cell activation was assessed in vitro and ex vivo, by measuring production of inflammatory mediators. In vitro assays were performed primarily with M-CSF plus IL-10 driven monocyte-derived M2c macrophages from healthy donors. Ex vivo assays were performed with fresh, patient-derived tumor samples in culture. To determine whether targeting VSIG4 can lead to an anti-tumor effect in vivo, syngeneic mouse models were dosed with anti-mouse VSIG4 antibodies and characterized for changes in tumor volume and immune cell populations.ResultsIn in vitro and ex vivo assays anti-VSIG4 antibodies repolarize M2 macrophages and induce an immune response culminating in T cell activation. Targeting VSIG4 upregulates pro-inflammatory cytokines in M2c macrophages, as well as upregulates pro-inflammatory myeloid-derived cytokines and T cell-derived cytokines in M2c macrophages co-cultured with autologous T cells in the presence of staphylococcal enterotoxin B (SEB) activation. To assess targeting VSIG4 in a relevant translational model, fresh, patient-derived tumor samples were treated ex vivo with anti-VSIG4. Across multiple tumor types, anti-VSIG4 treatment resulted in a significant upregulation of cytokines involved in TAM repolarization and T cell activation, and chemokines involved in immune cell recruitment, at levels greater than observed by treatment with anti-PD-1 or a clinical macrophage repolarizing agent (anti-ILT-4). In vivo, tumor growth inhibition is observed in syngeneic mouse models dosed with anti-mouse-VSIG4 alone and in combination with anti-PD-1.ConclusionsTaken together, these data suggest that VSIG4 represents a promising new target capable of stimulating an anti-cancer response via multiple key immune mechanisms.Referencesvan Lookeren Campagne M, Verschoor A. Pathogen clearance and immune adherence “revisited”: immuno-regulatory roles for CRIg. Semin Immunol 2018;37:4–11.Xu S, Sun Z, Li L, Liu J, He J, Song D, Shan G, Liu H, Wu X. Induction of T cells suppression by dendritic cells transfected with VSIG4 recombinant adenovirus. Immunol Lett 2010;128(1):46–50.Liao Y, Guo S, Chen Y, Cao D, Xu H, Yang C, Fei L, Ni B, Ruan Z. VSIG4 expression on macrophages facilitates lung cancer development. Lab Invest 2014;94(7):706–715.Roh J, Jeon Y, Lee A, Lee S, Kim Y, Sung C, Park C, Hong J, Yoon D, Suh C, Huh J, Choi I, Park C. The immune checkpoint molecule V-set Ig domain-containing 4 is an independent prognostic factor for multiple myeloma. Oncotarget 2017;8(35):58122–58132.Xu T, Jiang Y, Yan Y, Wang H, Lu C, Xu H, Li W, Fu D, Lu Y, Chen J. VSIG4 is highly expressed and correlated with poor prognosis of high-grade glioma patients. Am J Transl Res 2015;7(6):1172–1180.Byun J, Jeong D, Choi I, Lee D, Kang M, Jung K, Jeon Y, Kim Y, Jung E, Lee K, Sung M, Kim K. The significance of VSIG4 expression in ovarian cancer. Int J Gynecol Cancer 2017;27(5):872–878.Ethics ApprovalAll legal and ethical requirements were met with regards to the humane treatment of animals described in the study. The animal study was conducted in compliance with CRL IACUC under IACUC No. I033.

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CD20-TCB, a Novel T-Cell-Engaging Bispecific Antibody, Induces T-Cell-Mediated Killing in Relapsed or Refractory Non-Hodgkin Lymphoma: Biomarker Results From a Phase I Dose-Escalation Trial

Blood ◽

10.1182/blood-2019-123979 ◽

2019 ◽

Vol 134 (Supplement_1) ◽

pp. 5319-5319 ◽

Cited By ~ 2

Author(s):

Ann-Marie E Bröske ◽

Ian James ◽

Anton Belousov ◽

Enrique Gomez ◽

Marta Canamero ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

B Cells ◽

Board Of Directors ◽

T Cell Activation ◽

Research Funding ◽

Cell Activation ◽

Employment Equity ◽

Advisory Committees ◽

Equity Ownership

Introduction: CD20-TCB (RG6026) is a novel T-cell-engaging bispecific (TCB) antibody with a '2:1' molecular format that comprises two fragment antigen binding regions that bind CD20 (on the surface of B cells) and one that binds CD3 (on the surface of T cells). CD20-TCB offers the potential for increased tumor antigen avidity, rapid T-cell activation, and enhanced tumor cell killing versus other bispecific formats. The safety, tolerability, pharmacokinetics, biomarkers, and antitumor activity of CD20-TCB are currently being investigated in a multicenter Phase I dose-escalation trial (NP30179; NCT03075696). We recently presented preliminary clinical data demonstrating promising clinical activity in relapsed or refractory (R/R) non-Hodgkin lymphoma (NHL) patients with indolent or aggressive disease (Dickinson et al. ICML 2019). Here, we present preliminary blood and tissue biomarker analyses to explore modes of action, support optimal biological dose selection, and identify potential outcome predictors. Methods: For biomarker analyses, we performed immune profiling of peripheral blood by flow cytometry, analyzed plasma cytokine levels by ELISA, and characterized baseline and on-treatment tumor biopsies by immunohistochemistry/immunofluorescence assays and RNA sequencing. Biomarker data were obtained from 122 patients dosed with 0.005-25mg CD20-TCB. Results: CD20-TCB infusion led to a rapid and transient reduction in T cells in the peripheral circulation (T-cell margination) in all patients. T-cell margination reached nadir 6 hours after the first CD20-TCB infusion, and showed a strong association with CD20-TCB dose and receptor occupancy (RO%; as determined by Djebli et al. ASH 2019). Interestingly, rebound of T cells 160 hours after the first CD20-TCB infusion was associated with response to treatment. Responding patients showed long-term T-cell activation after the first infusion of CD20-TCB at doses from 0.6mg and above. T-cell activation was demonstrated by 2-4-fold elevation of T-cell activation markers such as Ki67, HLA-DR, PD-1, ICOS, OX40, and 4-1BB, which was sustained up to Cycle 5 (105 days). Analysis of paired pre- and on-treatment tumor biopsies (n=6) obtained before and 2-3 weeks after the first dose of CD20-TCB showed evidence of T-cell-mediated tumor cell killing. Analysis of archival and pre-treatment tumor biopsies (n=80) revealed that clinical responses were achieved irrespective of the amount of tumor T-cell infiltration at baseline. In contrast, preliminary baseline bulk tumor RNA sequencing data (n=46) showed upregulation of gene signatures associated with cell proliferation/Myc and T-cell subsets (effector vs exhausted-like) in non-responding patients. Conclusions: In this study, we demonstrated the mode of action of CD20-TCB, a novel bispecific antibody with promising clinical activity in R/R NHL. We also demonstrated that biomarker data on T-cell activation can support dose finding in conjunction with pharmacokinetics. Additional analysis is ongoing to evaluate response predictors and better characterize the population that will benefit most from T-cell mediated therapies. Disclosures Bröske: Roche: Employment, Equity Ownership. James:A4P Consulting Ltd: Consultancy. Belousov:Roche: Employment. Gomez:F. Hoffmann-La Roche Ltd: Employment. Canamero:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Ooi:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Grabole:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Wilson:F. Hoffmann-La Roche Ltd: Employment. Korfi:F. Hoffmann-La Roche Ltd: Consultancy. Kratochwil:F. Hoffmann-La Roche Ltd: Employment. Morcos:Roche: Employment, Equity Ownership. Ferlini:Roche: Employment, Equity Ownership. Thomas:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Dimier:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Moore:F. Hoffmann-La Roche Ltd: Employment, Equity Ownership. Bacac:Roche: Employment, Equity Ownership, Patents & Royalties: Patents, including the one on CD20-TCB. Weisser:Pharma Research and Early Development Roche Innovation Center Munich: Employment, Equity Ownership, Patents & Royalties. Dickinson:Merck Sharpe and Dohme: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Honoraria, Research Funding, Speakers Bureau; Takeda: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; GlaxoSmithKline: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau. OffLabel Disclosure: CD20-TCB (also known as RG6026, RO7082859) is a full-length, fully humanized, immunoglobulin G1 (IgG1), T-cell-engaging bispecific antibody with two fragment antigen binding (Fab) regions that bind to CD20 (on the surface of B cells) and one that binds to CD3 (on the surface of T cells) (2:1 format). The 2:1 molecular format of CD20-TCB, which incorporates bivalent binding to CD20 on B cells and monovalent binding to CD3 on T cells, redirects endogenous non-specific T cells to engage and eliminate malignant B cells. CD20-TCB is an investigational agent.

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The Ratio of Costimulatory Vs Coinhibitory Molecules on AML Cells Determines the CD33-BiTE® Mediated T-Cell Response

Blood ◽

10.1182/blood-2018-99-116297 ◽

2018 ◽

Vol 132 (Supplement 1) ◽

pp. 1349-1349

Author(s):

Anetta Marcinek ◽

Bettina Brauchle ◽

Dragica Udiljak ◽

Roman Kischel ◽

Peter Kufer ◽

...

Keyword(s):

Cell Proliferation ◽

T Cells ◽

T Cell ◽

Board Of Directors ◽

T Cell Activation ◽

Research Funding ◽

Cell Activation ◽

T Cell Proliferation ◽

Target Cells ◽

Advisory Committees

Abstract Bispecific T-cell engagers (BiTE® antibody constructs) represent a novel immunotherapeutic strategy relying on the recruitment of T cells against tumor cells independent of TCR specificity. In Acute Myeloid Leukemia (AML), CD33 represents a suitable target antigen with high expression levels in >90 % of primary AML samples (Krupka et al, 2014). A CD33-BiTE® antibody construct (AMG 330) was developed mediating cytotoxicity against primary AML in vitro although to a variable degree (Krupka et al, 2016). Several parameters have been identified which modulate AMG 330-mediated cytotoxicity, including CD33 expression level as well as effector to target cell (E:T) ratio. However, the exact mechanism of T-cell activation through BiTE® antibody constructs is only partly understood. Physiological T-cell activation is based on engagement of the T-cell receptor complex together with costimulatory molecules whereas the absence of positive costimulation leads to T-cell anergy. In line with this concept, we hypothesized that BiTE®-mediated cytotoxicity requires positive costimulatory signals on the target cells for T-cell activation. We hypothesize that the ratio of costimulatory and coinhibitory molecules on AML cells determines the susceptibility to AMG 330-mediated cytotoxicity independent of target antigen expression level. A stable expression system was established utilizing murine Ba/F3 cells expressing human CD33 ± CD80 ± CD86 ± PD-L1. Co-cultures of Ba/F3 constructs and T cells were performed in presence of AMG 330 or a control BiTE® (cBiTE®) (5 ng/ml). For some experiments, T cells were separated into naive (CD45RA+/CCR7+) vs memory (CD45RADIM) cells using fluorescence-activated cell sorting. After 3 days, specific lysis was determined by flow cytometry and calculated as % specific lysis = 100 × (1 - live CD33+ cellsAMG 330 / live CD33+ cellscBiTE). T-cell proliferation was defined as number of CD2+ cells on day 3 compared to day 0. The expression pattern of CD33, CD80, CD86 and PD-L1 on primary AML cells was evaluated by specific fluorescence intensity (SFI) using multiparameter flow cytometry. A sample was considered positive at an SFI of > 1.5. Characterized primary AML patient samples were used in a long-term culture assay to determine the influence of the checkpoint molecule expression profile on AMG 330-mediated cytotoxicity. CD33 single positive Ba/F3 cells were not lysed upon the addition of AMG 330 and allogeneic T cells. Cytotoxicity could be restored by expression of CD80, CD86 and CD80+CD86 with following tendency: CD80+CD86 >> CD80 > CD86 (see table 1). There was a direct correlation of T-cell proliferation to AMG 330 mediated cytotoxicity. Memory T cells showed increased cytotoxicity compared to naive T cells against the different Ba/F3 cell lines. The influence of co-inhibition was investigated by additionally transducing PD-L1 into the different Ba/F3 cells. This led to a reduced AMG 330-mediated cytotoxicity in all PD-L1 expressing Ba/F3 cells (Table 1). This was accompanied by a reduction in T-cell proliferation. Looking at the expression profile of CD80 and CD86 in primary AML samples, we observed expression of CD80 in 7/123 and of CD86 in 188/226 of cases (respectively 5.7 % and 83.2 %). When comparing AMG 330-mediated cytotoxicity against primary AML cells for patient pairs with similar CD33 expression levels, a higher CD86/PD-L1 ratio led to an increased AMG 330-mediated cytotoxicity compared to patient samples with a lower CD86/PD-L1 ratio (exemplary data: SFI CD33+: 81.7; SFI-ratio CD86/PD-L1: 4; specific cytotoxicity: 64.2 % vs. SFI CD33+: 89.5; SFI-ratio CD86/PD-L1: 15.9; specific cytotoxicity: 96.4 %). In summary, this data supports the hypothesis that AMG 330-mediated cytotoxicity and T-cell proliferation are influenced by the ratio of costimulatory and coinhibitory molecules on AML cells. Our data supports the notion that the checkpoint profile on AML, rather than one molecule by itself, determines T-cell response to AMG 330. Prospective analyses in clinical trials are needed to validate the relevance of checkpoint molecules on target cells as a predictive biomarker for response. Disclosures Marcinek: AMGEN Research Munich: Research Funding. Brauchle:AMGEN Inc.: Research Funding. Kischel:AMGEN: Employment. Kufer:AMGEN Research Munich: Employment. Subklewe:Pfizer: Membership on an entity's Board of Directors or advisory committees; Roche AG: Research Funding; AMGEN: Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Membership on an entity's Board of Directors or advisory committees, Research Funding.

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Cyclosporine-Romiplostim-IVIG Combination Therapy In Patients With Severe Immune Thrombocytopenia (ITP)

Blood ◽

10.1182/blood.v122.21.1085.1085 ◽

2013 ◽

Vol 122 (21) ◽

pp. 1085-1085

Author(s):

Sif Gudbrandsdottir ◽

Emily Leven ◽

Allison Imahiyerobo ◽

Soo Lee ◽

James B. Bussel

Keyword(s):

T Cell ◽

Combination Therapy ◽

Board Of Directors ◽

T Cell Activation ◽

Research Funding ◽

Cell Activation ◽

Primary Outcome ◽

Platelet Destruction ◽

Advisory Committees ◽

Platelet Production

Abstract Introduction In patients with ITP, a small proportion of children and adults are very unresponsive to treatment, do not respond to single agents, and may benefit from combination therapy with 1st and/or 2nd line agents. Studies have investigated combinations of 2nd-line immunosuppressive agents in patients with severe ITP, but none have been well validated because of small patient populations. Also, combinations of ≥ 2 chemotherapy agents increase concern regarding side effects. In this retrospective study, safety and efficacy of combination therapy with romiplostim, cyclosporine A (CSA) and IVIG were investigated. Romiplostim, a thrombopoietin receptor agonist (TPO-RA), stimulates platelet production, CSA inhibits T cell activation, and IVIG blocks antibody-mediated platelet destruction. Thus, 2 forms of platelet destruction as well as impaired production were simultaneously targeted with agents whose toxicity is non-overlapping Methods Adult and pediatric severe ITP patients treated with CSA-romiplostim-IVIG therapy at the Weill Cornell Medical College were included. 13/14 patients had been unresponsive to monotherapy with TPO-RA. Romiplostim was injected weekly in individually adjusted doses; CSA was taken at sub-transplant doses (100-200 ng/ml) to minimize toxicity; and IVIG was infused as needed. Primary outcome was platelet counts consistently ≥30,000. Secondary outcomes were reduction in dose or frequency of IVIG and/or reduction of romiplostim dose. Results 14 severe ITP patients (4 children) received the CSA-romiplostim-IVIG regimen for median 5 months (range 1-22 mos) (Table). Ten patients (71%) including 2 children met the primary outcome criteria and were responders (Figure). 2 responders no longer required IVIG; 3 more had less need for it. 1 responder discontinued romiplostim due to stable platelet counts; another 4 reduced their dose. 5 responders discontinued combination therapy: 1 due to sustained response (22 months); 1 due to pregnancy (6 months); 1 entered a clinical trial (5 months); 1 due to side effects of CSA (3 months); 1 died (5 months) from pre-existing cardiac disease. 2 responders received short courses of danazol: 1 during the first 2 weeks of combination therapy and 1 after 12 months when a bone marrow biopsy revealed fibrosis and romiplostim was discontinued. Adverse effects of CSA (headache, abdominal pain, diarrhea and peripheral neuropathy) were reported in 6 responders and 2 non-responders; 1 non-responder had worsened hypertension, which resolved upon discontinuation of CSA. 5 additional patients received mycophenolate mofetil (MMF) instead of CSA with TPO-RA and IVIG; 4 responded. Conclusion There has been increasing focus on T cells in ITP in the past few years. CSA inhibits T-cell activation, so the efficacy of CSA in combination with IVIG and stimulation of platelet production supports both the hypothesis that activated T cells contribute to unresponsiveness in ITP and that targeting different aspects of the pathophysiology of ITP may be highly effective. Reported responses of CSA monotherapy in ITP are 17/22 adults and 16/31 children with a relapse rate of 36%. Reported adults had received doses of CSA to maintain serum levels of 200-400 ng/mL and had failed only 1-4 treatments; none had received TPO-RA. In contrast, our responders had failed 5-8 treatments, failed TPO-RA, and apparently had lesser toxicity because of lower doses of CSA. CSA can optimally be used in combination with romiplostim and IVIG to manage patients with severe ITP; however, CSA toxicity requires monitoring and potentially adjustment of therapy. Studies are planned to further investigate the use of romiplostim and IVIG in combination with CSA and other T-cell agents such as MMF or sirolimus. Disclosures: Gudbrandsdottir: Amgen: Research Funding; GlaxoSmithKline: Research Funding. Bussel:Amgen: Family owns stock Other, Membership on an entity’s Board of Directors or advisory committees, Research Funding; Cangene: Research Funding; Genzyme: Research Funding; GlaxoSmithKline: Family owns stock, Family owns stock Other, Membership on an entity’s Board of Directors or advisory committees, Research Funding; IgG of America: Research Funding; Immunomedics: Research Funding; Ligand: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Eisai: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Shionogi: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Sysmex: Research Funding; Symphogen: Membership on an entity’s Board of Directors or advisory committees.

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Target Expression, Preclinical Activity and Mechanism of Action of EM801: A Novel First-in-Class Bcma T-Cell Bispecific Antibody for the Treatment of Multiple Myeloma

Blood ◽

10.1182/blood.v126.23.117.117 ◽

2015 ◽

Vol 126 (23) ◽

pp. 117-117 ◽

Cited By ~ 8

Author(s):

Anja Seckinger ◽

Jose Antonio Delgado ◽

Laura Moreno ◽

Brigitte Neuber ◽

Anna Grab ◽

...

Keyword(s):

Multiple Myeloma ◽

T Cells ◽

T Cell ◽

Board Of Directors ◽

T Cell Activation ◽

Mechanism Of Action ◽

Research Funding ◽

Advisory Committees

Abstract Background. T-cell bispecific antibodies (TCBs) simultaneously binding CD3 on T-cells and individual tumor antigens, activate T-cells and destroy tumor antigen carrying cells. B-cell maturation antigen (BCMA), a surface antigen reported to be expressed on normal and malignant plasma cells (PCs), could represent a potentially promising target for TCBs in multiple myeloma (MM). The Aim of our study was to: i) assess expression of BCMA in normal and malignant PCs as well as cells of the bone marrow (BM) microenvironment by gene expression profiling and flow cytometry to validate it as potential clinical target for TCBs; ii) to evaluate activity of EM801 as member of a novel class of BCMA-TCBs in vitro on primary myeloma cells and in vivo in the H929-xenograft reconstituted NOG mouse model; and iii) to delineate its mechanism of action. Results. Expression. We investigated the expression of BCMA in CD138-purified PCs from BM aspirates obtained from 726 patients including MGUS (n=62), asymptomatic (n=59) and symptomatic MM (605), as well as different BM cellular subsets from healthy donors (n=10 PCs; plasmablasts, memory B-cells, T-cells, CD34+, CD14+, CD15+, n=5 each; n=8 mesenchymal stromal cells) using Affymetrix DNA-microarrays. BCMA expression was observed in malignant PC from 723/726 (99.5%) MGUS and MM patients, 10/10 normal PCs and 5/5 plasmablasts; gene expression of BCMA was undetectable in all other normal BM subsets. Using multiparameter flow cytometry, BCMA surface expression on malignant PCs was confirmed in 40/40 patients while being absent on normal BM cells. BCMA is thus a potential target in virtually all myeloma patients. Activity. In vitro, EM801 induced concentration dependent significant cell death in malignant plasma cells in BM-samples of 21/28 (75%) previously untreated and 8/10 (80%) relapsed/refractory MM patients in concentrations ranging from 10pM to 30nM. No or only minor unspecific toxicity on cells of the BM microenvironment was observed. In vivo efficacy of EM801 was studied in a subcutaneous H929 myeloma cell line xenograft model in NOG (NOD/Shi-scid/IL-2Rγnull) mice reconstituted with human PBMCs. Three doses of EM801, i.e. 0.026, 0.26 and 2.6 nM/kg, the same doses of a BCMAxCD3-(scFv)2 and two control groups were investigated (n=9 mice/group). Three weekly intravenous doses were given, starting on day 19 after tumor cell injection when tumor volumes were 293±135 mm3. On day 47, all mice from control groups had their tumors grown beyond 2000 mm3 and were euthanized for ethical reasons. In contrast, at 2.6 nM/kg (0.5 mg/kg) EM801 tumor regression was already observed after the second i.v. injection in 6/9 animals and the tumor regressed to 16±3 mm3 on day 47. BCMAxCD3-(scFv)2 bispecific antibody without Fc did not show any efficacy at all doses studied. Regarding the mechanism of action, we first demonstrated that EM801 effectively binds myeloma cells and T-cells with a strength of 1622±410 pN (5-10 fold of control) as measured by atomic force microscopy. Secondly, increasing concentrations (0.03-30nM) of EM801 led to progressive T-cell activation in primary BM samples, with significantly increased levels of CD69 (P<0.001), CD25 (P<0.001) and HLADR (P=0.001) expression in both CD4 and CD8 T-cells as compared to an unspecific TCB. Thirdly, EM801 induced significant secretion of interferon-γ (19-3000 pg/ml), granzyme B (68-2986 pg/ml), and perforin (145-3712 pg/ml) as measured by ELISA, together explaining the strong in vitro and in vivo activity of EM801. Conclusions. BCMA is selectively expressed at the RNA (723/726) and protein (40/40) levels on malignant PCs from virtually all MM patients, and thus represents a promising TCB-target. The novel BCMA-TCB EM801 was effective in vitro in 29/38 (76%) primary MM patients' BM samples at picomolar to low nanomolar concentrations, easily achievable in vivo in patients, as well as in the H929-xenograft reconstituted NOG mouse model at 0.5 mg/kg once a week. Neither in vitro (the BM microenvironment) nor in vivo the compound shows significant toxicity or side effects. EM801 confers cytotoxicity by effectively coupling T-cells with malignant PCs, inducing T-cell activation, secretion of interferon-γ, granzyme B and perforin, and thereby effectively killing malignant PCs. EM801 is thus a promising new compound for the treatment of multiple myeloma to be investigated in clinical phase I/II trials. Disclosures Seckinger: EngMab AG: Research Funding; Takeda: Other: Travel grant. Neuber:EngMab AG: Research Funding. Vu:EngMab AG: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Strein:BB Biotech AG: Membership on an entity's Board of Directors or advisory committees; Novimmune SA: Membership on an entity's Board of Directors or advisory committees; EngMab AG: Employment, Equity Ownership, Membership on an entity's Board of Directors or advisory committees. Hundemer:EngMab AG: Research Funding. San Miguel:Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; Janssen-Cilag: Honoraria; Millennium: Honoraria; Novartis: Honoraria; Sanofi-Aventis: Honoraria; Onyx: Honoraria. Hose:Takeda: Other: Travel grant; EngMab AG: Research Funding. Paiva:Celgene: Consultancy; Janssen: Consultancy; Binding Site: Consultancy; BD Bioscience: Consultancy; EngMab AG: Research Funding; Onyx: Consultancy; Millenium: Consultancy; Sanofi: Consultancy.

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Group BStreptococcusInduces a Robust IFN-γResponse by CD4+T Cells in anIn VitroandIn VivoModel

Journal of Immunology Research ◽

10.1155/2016/5290604 ◽

2016 ◽

Vol 2016 ◽

pp. 1-12 ◽

Cited By ~ 9

Author(s):

Damian Clarke ◽

Corinne Letendre ◽

Marie-Pier Lecours ◽

Paul Lemire ◽

Tristan Galbas ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Capsular Polysaccharide ◽

Ex Vivo ◽

Specific Cell ◽

Proinflammatory Response

Group BStreptococcus(GBS) serotype III causes life-threatening infections. Cytokines have emerged as important players for the control of disease, particularly IFN-γ. Although potential sources of this cytokine have been proposed, no specific cell line has ever been described as a leading contributor. In this study, CD4+T cell activation profiles in response to GBS were evaluated throughin vivo,ex vivo,andin vitroapproaches. Total splenocytes readily produce a type 1 proinflammatory response by releasing IFN-γ, TNF-α, and IL-6 and actively recruit T cells via chemokines like CXCL9, CXCL10, and CCL3. Responding CD4+T cells differentiate into Th1 cells producing large amounts of IFN-γ, TNF-α, and IL-2.In vitrostudies using dendritic cell and CD4+T cell cocultures infected with wild-type GBS or a nonencapsulated mutant suggested that GBS capsular polysaccharide, one of the major bacterial virulence factors, differentially modulates surface expression of CD69 and IFN-γproduction. Overall, CD4+T cells are important producers of IFN-γand might thus influence the course of GBS infection through the expression balance of this cytokine.

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