scholarly journals P14.47 Tissue immune markers for central nervous system germinoma

2019 ◽  
Vol 21 (Supplement_3) ◽  
pp. iii77-iii78 ◽  
Author(s):  
A K CHAN ◽  
Z F Shi ◽  
K W Lo ◽  
H K Ng ◽  
C C Lau
Keyword(s):  
T Cells ◽  
T Cell ◽  
Immune Cells ◽  
Immune Cell ◽  
Hla Class I ◽  
Class I ◽  
Cytotoxic T Cell ◽  
T Helper ◽  
The Mean ◽  
Immune Cell Infiltrates

Abstract BACKGROUND Germinoma is the commonest CNS germ cell tumor. An important histological feature is prominent immune cell infiltrates. The composition of such immune cell infiltrates remains under-investigated in the literature. MATERIAL AND METHODS We collected a cohort of 40 cases of intra-cranial germinomas and examined the clinical and histopathological features. The tumor infiltrating immune cells were characterized by immunohistochemistry and image analysis. RESULTS Across the cohort, the mean positivity ± SE of CD3-positive T cell and CD20-positive B cells was 31.2% ± 3.1% and 15.2% ± 2.2%, respectively (p<0.001). The mean positivity of CD4-positive T helper cell and CD8-positive cytotoxic T cell was 19% ± 2.3% and 14.3% ± 1.7%, respectively (p<0.001). PD-L1 expression was detected in 50% of the cases and was observed exclusively in immune cells but not in neoplastic cells. Germinomas with positive PD-L1 expression had significantly more abundant CD3-positive T cells (p=0.001), CD4-positive T helper cells (p<0.001) and CD8-positive cytotoxic T cells (p=0.004) as compared with those lacking PD-L1 expression. Immunostain for HLA-A and HLA-B revealed loss of HLA class I expression occurring in 92.5% of the germinomas. Loss of HLA class I expression was associated with less abundant CD3-positive T cells (p=0.04). CONCLUSION Taken together, the predominant T cells infiltrate and PD-L1 expression suggest anti-PD-L1 therapeutic agents as potential novel treatment option for germinoma patients. The loss of HLA class I may represent one of the mechanisms for tumor immune escape in germinoma.

Abstract 095: CD74 Deficient Mice are Resistant to Toll-Like Receptor-Induced Preeclampsia

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Mohamad Hatahet ◽  
Olga Y Gasheva ◽  
Valorie L Chiasson ◽  
Piyali Chatterjee ◽  
Kelsey R Bounds ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Endothelial Dysfunction ◽  
Mhc Class Ii ◽  
Immune Cells ◽  
Immune Cell ◽  
Class Ii ◽  
Poly I:C ◽  
Hypertensive Disorder ◽  
Toll Like Receptor

Preeclampsia (PE) is a pregnancy-specific hypertensive disorder characterized by vascular endothelial dysfunction and excessive immunity and inflammation. Activation of the dsRNA receptor Toll-like receptor 3 (TLR3) or the ssRNA receptor TLR7 elicits a pregnancy-dependent PE-like syndrome in mice by inducing a pro-inflammatory immune response. CD74 (MHC Class II invariant chain) acts as a chaperone for MHC Class II surface expression on immune cells during antigen presentation and is cleaved into Class II-Associated Invariant Peptide (CLIP) following polyclonal activation of immune cell TLRs. The presence of CLIP in the groove of MHC Class II prevents T cell-dependent death leading to persistent immune cell activation. We hypothesized that genetic deletion of CD74 and subsequent depletion of CLIP on immune cells prevents TLR-induced immune responses and the development of PE in mice. Pregnant WT and CD74 KO mice were given i.p. injections of normal saline (P), poly I:C (TLR3 agonist; P-PIC), or R837 (TLR7 agonist; P-R837) on gestational days 13, 15, and 17 and euthanized on day 18. P-PIC and P-R837 WT mice had significantly increased splenic levels of pro-inflammatory CD3+/gd T cells and plasma levels of the gd T cell-derived cytokines IFNg, TNFa, and IL-17 compared to P WT mice whereas P-PIC and P-R837 CD74 KO mice had significantly increased anti-inflammatory CD3+/gd T cells and no significant increases in plasma IFNg, TNFa, and IL-17 levels. P-PIC and P-R837 CD74 KO mice did not develop the hypertension (gd17 SBP in mmHg: P WT=102±3, P CD74 KO=100±3, P-PIC WT=147±4*, P-PIC CD74 KO=95±3, P-R837 WT=133±2*, P-R837 CD74 KO=97±1; *p<0.05 vs. P WT), endothelial dysfunction, proteinuria, or placental necrosis seen in P-PIC and P-R837 WT mice. In conclusion, CD74 is crucial for the development of TLR-induced PE-like symptoms in mice and CD74/CLIP depletion may be a promising therapeutic target for women with PE.

Single Cell Profiling Reveals Unique CXCL13 Positive T Cell Subsets in the Tumor Microenvironment of Lymphocyte Rich Classic Hodgkin Lymphoma

Blood ◽  
2020 ◽  
Vol 136 (Supplement 1) ◽  
pp. 32-33
Author(s):  
Tomohiro Aoki ◽  
Lauren C. Chong ◽  
Katsuyoshi Takata ◽  
Katy Milne ◽  
Elizabeth Chavez ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cells ◽  
Single Cell ◽  
Immune Cells ◽  
Research Funding ◽  
Immune Cell ◽  
Expression Patterns ◽  
The Other ◽  
Tfh Cells

Introduction: Classic Hodgkin lymphoma (CHL) features a unique crosstalk between malignant cells and different types of normal immune cells in the tumor-microenvironment (TME). On the basis of histomorphologic and immunophenotypic features of the malignant Hodgkin and Reed-Sternberg (HRS) cells and infiltrating immune cells, four histological subtypes of CHL are recognized: Nodular sclerosing (NS), Mixed cellularity, Lymphocyte-rich (LR) and Lymphocyte-depleted CHL. Recently, our group described the high abundance of various types of immunosuppressive CD4+ T cells including LAG3+ and/or CTLA4+ cells in the TME of CHL using single cell RNA sequencing (scRNAseq). However, the TME of LR-CHL has not been well characterized due to the rarity of the disease. In this study, we aimed at characterizing the immune cell profile of LR-CHL at single cell resolution. METHODS: We performed scRNAseq on cell suspensions collected from lymph nodes of 28 primary CHL patients, including 11 NS, 9 MC and 8 LR samples, with 5 reactive lymph nodes (RLN) serving as normal controls. We merged the expression data from all cells (CHL and RLN) and performed batch correction and normalization. We also performed single- and multi-color immunohistochemistry (IHC) on tissue microarray (TMA) slides from the same patients. In addition, an independent validation cohort of 31 pre-treatment LR-CHL samples assembled on a TMA, were also evaluated by IHC. Results: A total of 23 phenotypic cell clusters were identified using unsupervised clustering (PhenoGraph). We assigned each cluster to a cell type based on the expression of genes described in published transcriptome data of sorted immune cells and known canonical markers. While most immune cell phenotypes were present in all pathological subtypes, we observed a lower abundance of regulatory T cells (Tregs) in LR-CHL in comparison to the other CHL subtypes. Conversely, we found that B cells were enriched in LR-CHL when compared to the other subtypes and specifically, all four naïve B-cell clusters were quantitatively dominated by cells derived from the LR-CHL samples. T follicular helper (TFH) cells support antibody response and differentiation of B cells. Our data show the preferential enrichment of TFH in LR-CHL as compared to other CHL subtypes, but TFH cells were still less frequent compared to RLN. Of note, Chemokine C-X-C motif ligand 13 (CXCL13) was identified as the most up-regulated gene in LR compared to RLN. CXCL13, which is a ligand of C-X-C motif receptor 5 (CXCR5) is well known as a B-cell attractant via the CXCR5-CXCL13 axis. Analyzing co-expression patterns on the single cell level revealed that the majority of CXCL13+ T cells co-expressed PD-1 and ICOS, which is known as a universal TFH marker, but co-expression of CXCR5, another common TFH marker, was variable. Notably, classical TFH cells co-expressing CXCR5 and PD-1 were significantly enriched in RLN, whereas PD-1+ CXCL13+ CXCR5- CD4+ T cells were significantly enriched in LR-CHL. These co-expression patterns were validated using flow cytometry. Moreover, the expression of CXCR5 on naïve B cells in the TME was increased in LR-CHL compared to the other CHL subtypes We next sought to understand the spatial relationship between CXCL13+ T cells and malignant HRS cells. IHC of all cases revealed that CXCL13+ T cells were significantly enriched in the LR-CHL TME compared to other subtypes of CHL, and 46% of the LR-CHL cases showed CXCL13+ T cell rosettes closely surrounding HRS cells. Since PD-1+ T cell rosettes are known as a specific feature of LR-CHL, we confirmed co-expression of PD-1 in the rosetting cells by IHC in these cases. Conclusions: Our results reveal a unique TME composition in LR-CHL. LR-CHL seems to be distinctly characterized among the CHL subtypes by enrichment of CXCR5+ naïve B cells and CD4+ CXCL13+ PD-1+ T cells, indicating the importance of the CXCR5-CXCL13 axis in the pathogenesis of LR-CHL. Figure Disclosures Savage: BeiGene: Other: Steering Committee; Merck, BMS, Seattle Genetics, Gilead, AstraZeneca, AbbVie: Honoraria; Roche (institutional): Research Funding; Merck, BMS, Seattle Genetics, Gilead, AstraZeneca, AbbVie, Servier: Consultancy. Scott:Janssen: Consultancy, Research Funding; Celgene: Consultancy; NanoString: Patents & Royalties: Named inventor on a patent licensed to NanoString, Research Funding; NIH: Consultancy, Other: Co-inventor on a patent related to the MCL35 assay filed at the National Institutes of Health, United States of America.; Roche/Genentech: Research Funding; Abbvie: Consultancy; AstraZeneca: Consultancy. Steidl:AbbVie: Consultancy; Roche: Consultancy; Curis Inc: Consultancy; Juno Therapeutics: Consultancy; Bayer: Consultancy; Seattle Genetics: Consultancy; Bristol-Myers Squibb: Research Funding.

scholarly journals Peptide vaccination directed against IDO1-expressing immune cells elicits CD8+ and CD4+ T-cell-mediated antitumor immunity and enhanced anti-PD1 responses

2020 ◽  
Vol 8 (2) ◽  
pp. e000605
Author(s):  
Souvik Dey ◽  
Erika Sutanto-Ward ◽  
Katharina L Kopp ◽  
James DuHadaway ◽  
Arpita Mondal ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Growth ◽  
Mhc Class I ◽  
Adoptive Transfer ◽  
Immune Cells ◽  
Class Ii ◽  
T Cell Response ◽  
Class I ◽  
Antitumor Effects

BackgroundThe tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase 1 (IDO1), which subverts T-cell immunity at multiple levels, is itself subject to inherent T-cell reactivity. This intriguing deviation from central tolerance has been interpreted as counterbalancing IDO1-mediated immunosuppression. Based on this hypothesis, clinical studies employing an IDO1 peptide-based vaccine approach for cancer treatment have been initiated, but there remains a pressing need to further investigate the immunological ramifications of stimulating the anti-IDO1 T-cell response in this manner.MethodsCT26 colon carcinoma tumors were evaluated for expression of IDO1 protein by western blot analysis, immunofluorescence microscopy and flow cytometry. Mouse IDO1-derived peptides, predicted to bind either major histocompatibility complex (MHC) class I or II of the H2d BALB/c strain, were emulsified in 50% Montanide for prophylactic or therapeutic vaccine treatment of CT26 tumor-bearing mice initiated either 7 days prior to or following tumor cell injection, respectively. In some therapeutic treatment experiments, administration of programmed cell death protein 1-binding antibody (anti-PD1 antibody) or epacadostat was concurrently initiated. Tumor size was determined by caliper measurements and comparative tumor growth suppression was assessed by longitudinal analyses of tumor growth data. For adoptive transfer, T cells from complete responder animals were isolated using paramagnetic beads and fluorescence-activated cell sorting.ResultsThis study identifies mouse MHC class I-directed and II-directed, IDO1-derived peptides capable of eliciting antitumor responses, despite finding IDO1 expressed exclusively in tumor-infiltrating immune cells. Treatment of established tumors with anti-PD1 antibody and class I-directed but not class II-directed IDO1 peptide vaccines produced an enhanced antitumor response. Likewise, class I-directed and II-directed IDO1 peptides elicited an enhanced combinatorial response, suggesting distinct mechanisms of action. Consistent with this interpretation, adoptive transfer of isolated CD8+ T cells from class I and CD4+ T cells from class II peptide-vaccinated responder mice delayed tumor growth. The class II-directed response was completely IDO1-dependent while the class I-directed response included an IDO1-independent component consistent with antigen spread.ConclusionsThe in vivo antitumor effects demonstrated with IDO1-based vaccines via targeting of the tumor microenvironment highlight the utility of mouse models for further exploration and refinement of this novel vaccine-based approach to IDO1-directed cancer therapy and its potential to improve patient response rates to anti-PD1 therapy.

scholarly journals HLA Class I-Restricted Cytotoxic T-Cell Epitopes of the Respiratory Syncytial Virus Fusion Protein

2000 ◽  
Vol 74 (21) ◽  
pp. 10240-10244 ◽  
Author(s):  
A. H. Brandenburg ◽  
L. de Waal ◽  
H. H. Timmerman ◽  
P. Hoogerhout ◽  
R. L. de Swart ◽  
...  
Keyword(s):  
Respiratory Syncytial Virus ◽  
T Cell ◽  
Cytotoxic T Lymphocytes ◽  
Hla Class I ◽  
Class I ◽  
Cytotoxic T Cell ◽  
T Cell Epitopes ◽  
Cell Clones ◽  
Rsv Infection ◽  
Syncytial Virus

ABSTRACT Virus-specific cytotoxic T lymphocytes (CTL) play a major role in the clearance of respiratory syncytial virus (RSV) infection. We have generated cytotoxic T-cell clones (TCC) from two infants who had just recovered from severe RSV infection. These TCC were functionally characterized and used to identify HLA class I (B57 and C12)-restricted CTL epitopes of RSV.

scholarly journals T-cell malignancies with mature phenotypes: altered cell cycle regulation by HLA class I molecules

Blood ◽  
1991 ◽  
Vol 78 (8) ◽  
pp. 2045-2052 ◽  
Author(s):  
MC Turco ◽  
F Alfinito ◽  
M De Felice ◽  
A Lamberti ◽  
S Ferrone ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Dna Synthesis ◽  
Hla Class I ◽  
Class I ◽  
Mitogenic Effect ◽  
Prolymphocytic Leukemia ◽  
T Lymphocyte Proliferation ◽  
Hla Class I Molecules

Abstract Soluble anti-HLA class I monoclonal antibodies (MoAbs) modulate normal T-lymphocyte proliferation induced via the CD3/Ti and the CD2 pathway, but do not induce proliferation of normal T lymphocytes in the absence of additional mitogenic stimuli. In this report, we show that anti-HLA class I MoAbs induce DNA synthesis in peripheral blood mononuclear cells from a patient with a CD4+CD8+T-prolymphocytic leukemia (T-PLL) and from a patient with a CD4-CD8+ T-chronic lymphocytic leukemia (T- CLL), in the absence of detectable additional mitogenic stimuli. Proliferation of leukemic T cells is induced by both whole Igs and Fab' fragments of anti-HLA class I MoAbs, arguing in favor of their direct interactions with the proliferating cells as the mechanism underlying the mitogenic effect. This interpretation is also supported by the ability of anti-HLA class I MoAbs to induce proliferation of leukemic T- cell preparations, depleted of accessory cells. DNA synthesis in T-CLL and T-PLL cells is preceded by expression of G1-specific messenger RNAs, ie. c-myc, 2F1, Tac, and interferon-gamma, in activated cells. Cell proliferation is inhibited by the protein kinase C inhibitor H7, indicating that activation of this enzyme is required for the mitogenic effect of anti-HLA class I MoAbs. The latter inhibit the proliferation of T-CLL cells as well as that of normal T cells stimulated with anti- CD3 MoAbs and enhance that of both types of cells stimulated with anti- CD2 MoAbs. In addition, anti-HLA class I MoAb Q6/64 in combination with anti-CD2 MoAb 9.6 or MoAb 9–1 induces proliferation of leukemic T cells to a greater extent than the individual MoAbs, but is not mitogenic for normal T cells. Anti-HLA class I MoAbs restore the cytolytic activity of T-CLL cells that is lost after 5 days of incubation of control medium, suggesting that HLA class I antigens may mediate a signal contributing to the activation state. The present results indicate that leukemic T-cell proliferation can be triggered via HLA class I molecules and suggest a potential role for these antigens in the in vivo growth of malignant clones.

scholarly journals Fas-Independent Apoptosis of Activated T Cells Induced by Antibodies to the HLA Class I α1 Domain

Blood ◽  
1997 ◽  
Vol 90 (9) ◽  
pp. 3629-3639 ◽  
Author(s):  
Laurent Genestier ◽  
Romain Paillot ◽  
Nathalie Bonnefoy-Berard ◽  
Geneviéve Meffre ◽  
Monique Flacher ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Heavy Chain ◽  
Hla Class I ◽  
Class I ◽  
T Cell Proliferation ◽  
Activated T Cells ◽  
Hla Class I Molecules

Abstract In addition to their major function in antigen presentation and natural killer cell activity regulation, HLA class I molecules may modulate T-cell activation and proliferation. Monoclonal antibodies (MoAbs) that recognize distinct epitopes of HLA class I molecules were reported to interfere with T-cell proliferation. We show here that two MoAbs (mouse MoAb90 and rat YTH862) that bind to an epitope of the α1 domain of HLA class I heavy chain induce apoptotic cell death of activated, but not resting, peripheral T lymphocytes. Other reference anti-HLA class I antibodies specific for distinct epitopes of the α1 (B9.12.1), α2 (W6/32), or α3 (TP25.99) domains of the heavy chain decreased T-cell proliferation but had little or no apoptotic effect. Apoptosis shown by DNA fragmentation, phosphatidylserine externalization, and decrease of mitochondrial transmembrane potential was observed whatever the type of T-cell activator. Apoptosis did not result from Fas/Fas-L interaction and distinct though partly overlapping populations of activated T cells were susceptible to Fas– and HLA class I–mediated apoptosis, respectively. Induction of apoptosis did not require HLA class I cross-linking inasmuch as it could be observed with monovalent Fab′ fragments. The data indicate that MoAb90 and YTH862 directed against the α1 domain of HLA class I trigger apoptosis of activated T lymphocytes by a pathway which does not involve Fas-ligand.

scholarly journals Global immune characterization of HBV/HCV-related hepatocellular carcinoma identifies macrophage and T-cell subsets associated with disease progression

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Guohe Song ◽  
Yang Shi ◽  
Meiying Zhang ◽  
Shyamal Goswami ◽  
Saifullah Afridi ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
T Cells ◽  
T Cell ◽  
Single Cell ◽  
Immune Cells ◽  
Immune Cell ◽  
T Cell Subsets ◽  
M2 Macrophage ◽  
Advanced Hcc ◽  
Immune Cell Subsets

AbstractDiverse immune cells in the tumor microenvironment form a complex ecosystem, but our knowledge of their heterogeneity and dynamics within hepatocellular carcinoma (HCC) still remains limited. To assess the plasticity and phenotypes of immune cells within HBV/HCV-related HCC microenvironment at single-cell level, we performed single-cell RNA sequencing on 41,698 immune cells from seven pairs of HBV/HCV-related HCC tumors and non-tumor liver tissues. We combined bio-informatic analyses, flow cytometry, and multiplex immunohistochemistry to assess the heterogeneity of different immune cell subsets in functional characteristics, transcriptional regulation, phenotypic switching, and interactions. We identified 29 immune cell subsets of myeloid cells, NK cells, and lymphocytes with unique transcriptomic profiles in HCC. A highly complex immunological network was shaped by diverse immune cell subsets that can transit among different states and mutually interact. Notably, we identified a subset of M2 macrophage with high expression of CCL18 and transcription factor CREM that was enriched in advanced HCC patients, and potentially participated in tumor progression. We also detected a new subset of activated CD8+ T cells highly expressing XCL1 that correlated with better patient survival rates. Meanwhile, distinct transcriptomic signatures, cytotoxic phenotypes, and evolution trajectory of effector CD8+ T cells from early-stage to advanced HCC were also identified. Our study provides insight into the immune microenvironment in HBV/HCV-related HCC and highlights novel macrophage and T-cell subsets that could be further exploited in future immunotherapy.

Analysis of Memory T Lymphocytes Activity Following Stimulation with HLA-A24, A1 and Cw4 Restricted 9- and 10-mer Cytomegalovirus pp65 Overlapping Peptides.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2876-2876
Author(s):  
Monica Ghei ◽  
David F. Stroncek ◽  
Maurizio Provenzano
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Immune Therapy ◽  
Hla Class I ◽  
Class I ◽  
Specific Ctls ◽  
Over Time

Abstract In healthy subjects, primary infection with Cytomegalovirus (CMV) is usually mild or asymptomatic and is effectively controlled by the cell-mediated immune response. However, in immune compromised individuals, such as those with AIDS or after bone marrow transplantation, CMV reactivation is associated with significant morbidity until the individual’s immune system is completely reconstituted. One means of preventing post-transplant CMV infection is adoptive immunotherapy using CMV-specific cytotoxic T cells (CTLs) from the transplant donor. Several 9- and 10-mer HLA class I restricted peptides derived from the immune dominant CMV 65 kd matrix phosphoprotein (pp65) have been shown to produce CMV-specific CTLs. Two overlapping HLA-A24 restricted peptides have been specifically described: pp65 341–349 and pp65 341–350. These are 9- and 10-mer peptides that overlap except for the last amino acid phenylalanine (F) at the C-terminus [QYDPVAALF(F)]. Despite their similarity, the ability of these peptides to induce a T cell response has been reported to differ. Although it has been generally accepted that a unique CMV peptide is bound and presented by each separate HLA class I molecule, recent studies suggest that certain peptides are more promiscuous and may be presented by more than one HLA Class I antigen. For example, the 9-mer pp65 341–349 has been shown to stimulate CTLs from both HLA-A24 and Cw4 donors, while the 10-mer pp65 341–350 has been shown to be reactive with both HLA-A24 and A1 donors. The current investigation sought to compare the potency of these two peptides and determine the optimum peptide size for effective CMV adoptive immune therapy. Both peptides were tested for their ability to stimulate CMV-specific CTLs in HLA-A24, HLA-A1, and HLA-Cw4 restriction. In addition, a pp65 16-mer that included the 9- and 10-mers was tested for its ability to reactivate either CD8+ or CD4+ memory T cells. IFN-γ mRNA transcript as well as protein production were measured by in vitro cell culture assays. Peptide stimulations were performed on isolated CD8 and CD4 T lymphocytes by inducing the cells for 3 hours after a 2-week in vitro sensitization. The goal of the investigation was to determine whether both the 9- and the 10-mer peptides maintained high levels of CTL stimulation over time for all HLA restrictions studied. Moreover, it was important to investigate whether stimulation with the 16-mer, followed by restimulation by the two smaller peptides embedded within the larger sequence, led to effective T cell memory immune response. The 9- and 10-mer peptides effectively stimulated CTLs from HLA-A24, HLA-A1, and HLA-Cw4 CMV seropositive donors. Although both 9- and 10-mer were able to maintain high levels of stimulation over time for all restrictions, the 9-mer induced highest responses in cells expressing HLA-A24 (S.I. 4.07–528) or HLA-Cw4 (S.I. 4.15–483) while the 10-mer induced highest responses in cells expressing HLA-A24 (S.I. 3.5–528) or HLA-A1 (S.I. 8.25–615). The 16-mer peptide was also able to stimulate T cells from all HLA-A24, A1 and Cw4 donors (S.I. 6.95, 4.96, 5.02) at levels that are well maintained over time. This data confirmed that both the 9- and the 10-mer peptides are promiscuous and not restricted to a single HLA antigen. These peptides that have the ability to produce CMV-specific CTLs in patients with several different HLA types present a practical advantage over peptides that are restricted only to a single HLA type, and thus are optimal for CMV adoptive immune therapy.

Leukemic Blasts Acting as Host Antigen Presenting Cells Trigger a Combined CD4 and CD8 Allo-Immune Response Directed Against Mismatched HLA Class I.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 5030-5030
Author(s):  
Avital Amir ◽  
Renate S. Hagendoorn ◽  
Erik W.A. Marijt ◽  
Roelof Willemze ◽  
J.H. Frederik Falkenburg ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Hla Class I ◽  
Cd8 T Cell ◽  
Class I ◽  
Mixed Chimerism ◽  
Target Cells ◽  
Hla Dr ◽  
Donor T Cells

Abstract Single HLA locus mismatched stem cell transplantation (SCT) is applied in patients with hematological malignancies who may benefit from allogeneic transplantation but lack an HLA-matched donor. Although HLA disparity between patient and donor increases the risk of developing GVHD, the relative risk of GVHD after single HLA locus mismatched SCT is only 1.5 fold. In view of the high frequency of allo-HLA reactive T-cells, which is about 1000-fold higher than the frequencies of minor histocompatibility antigen specific T-cells, this risk increase is lower than could be expected. Since almost all nucleated cells express HLA class I, one would expect all single HLA class I mismatched transplanted patients to develop severe GVHD. We hypothesized therefore that the presentation of the HLA class I mismatched allele on nucleated cells of the patient is not sufficient to elicit an effective allo-immune response. We characterized the allo-immune response in a patient with acute myeloid leukemia (AML) who was treated with a T-cell depleted SCT from a sibling donor who was HLA identical except for an HLA-A2 crossover. Six months after SCT, donor lymphocyte infusion (DLI) of 2.5*10e6 T-cells/kg was given for mixed chimerism comprising 99% T-cells of patient origin. No clinical response and no GVHD developed. Twelve months after SCT 95% of T-cells were still of patient origin, and AML relapse occurred with 9% blasts in bone marrow for which a second DLI containing 7.5*10e6 T-cells/kg was given. Five weeks after the DLI the patient died of grade IV GVHD. During the GVHD, conversion to donor chimerism developed. In peripheral blood of the patient 90% of CD8 and 40% of CD4 donor T-cells were activated as determined by HLA-DR expression. To analyze the nature of the immune response, the activated CD8 and CD4 donor T-cells were single cell sorted, expanded and tested for alloreactivity and HLA restriction using cytotoxicity and cytokine production assays against a panel of target cells blocked with different HLA-mAbs. 82% of the CD8 T-cell clones were alloreactive and restricted to the allo-HLA-A2. The response was highly polyclonal as shown by the usage of different T-cell receptor Vβ chains with different CDR3 sequences. 26% of the CD4 clones were alloreactive and this response was also polyclonal. The CD4 clones were HLA-DR1 restricted and recognized donor EBV-LCL transduced with HLA-A2, indicating that the peptide recognized in HLA-DR1 was derived from the mismatched HLA-A2 molecule. The recognized epitope was demonstrated to comprise AA 103–120 derived from a hypervariable region of HLA-A2. At the time of the first DLI, only HLA class I expressing T-cells and non-hematopoietic patient derived cells were present, capable of activating the CD8 T-cells but not of triggering the CD4 response. Leukemic blasts present at the time of the second DLI, however, expressed both HLA-DR and HLA class I, and were shown to activate the CD4 as well as the CD8 clones. We hypothesize that the HLA class II expression on hematopoietic cells of the patient at the time of the relapse was essential for the development of this immune response. In conclusion, these results indicate a role for patient leukemic blasts acting as host APCs in initiating the GVH response by activating both a CD4 and CD8 T-cell response in an HLA class I mismatched setting.

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