scholarly journals Ineffective Cellular Immune Response Associated with T-Cell Apoptosis in Susceptible Mycobacterium bovisBCG-Infected Mice

2000 ◽  
Vol 68 (7) ◽  
pp. 4264-4273 ◽  
Author(s):  
Laurent Kremer ◽  
Jérôme Estaquier ◽  
Isabelle Wolowczuk ◽  
Franck Biet ◽  
Jean-Claude Ameisen ◽  
...  
Keyword(s):  
Immune Response ◽  
Cell Proliferation ◽  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
Cell Apoptosis ◽  
T Cell Proliferation ◽  
T Cell Apoptosis ◽  
Tnf Α

ABSTRACT It has previously been reported that inhibition of delayed-type hypersensitivity-mediating functions of T cells during mycobacterial infection in mice is haplotype dependent. In the present study, we show that Mycobacterium bovis BCG infection induced, in susceptible C57BL/6 and BALB/c mice but not in resistant C3H/HeJ and DBA/2 mice, an important splenomegaly. An in vitro defect in T-cell proliferation in response to T-cell receptor (TCR) stimulation with mitogens or anti-CD3 antibodies was associated with enhanced levels of CD4+ and CD8+ T-cell apoptosis in susceptible but not in resistant mice 2 weeks after infection. Further investigations of C57BL/6 and C3H/HeJ mice revealed that in vivo splenomegaly was associated with destruction of the lymphoid tissue architecture, liver cellular infiltrates, and increased numbers of apoptotic cells in both spleen and liver tissue sections. Infection of C57BL/6 mice but not of C3H/HeJ mice induced massive production of tumor necrosis factor alpha (TNF-α) in serum, as well as an increase in Fas and Fas ligand (FasL) expression in T cells. In vitro addition of neutralizing anti-TNF-α antibodies led to a significant reduction in CD3-induced T-cell apoptosis of both CD4+ and CD8+ T cells of C57BL/6 mice, while the blockade of Fas-FasL interactions reduced apoptosis only in CD4+ but not in CD8+ T cells. Together, these results suggest that TNF-α and Fas-FasL interactions play a role in the activation-induced cell death (AICD) process associated with a defect in T-cell proliferation of the susceptible C57BL/6 mice. T-cell death by apoptosis may represent one of the important components of the ineffective immune response against mycobacterium-induced immunopathology in susceptible hosts.

scholarly journals Low-Dose Decitabine Augments the Activation and Anti-Tumor Immune Response of IFN-γ+ CD4+ T Cells Through Enhancing IκBα Degradation and NF-κB Activation

2021 ◽  
Vol 9 ◽  
Author(s):  
Xiang Li ◽  
Liang Dong ◽  
Jiejie Liu ◽  
Chunmeng Wang ◽  
Yan Zhang ◽  
...  
Keyword(s):  
Immune Response ◽  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Low Dose ◽  
T Cell Proliferation ◽  
Ifn Γ ◽  
Iκbα Degradation

BackgroundCD4+ T cells play multiple roles in controlling tumor growth and increasing IFN-γ+ T-helper 1 cell population could promote cell-mediated anti-tumor immune response. We have previously showed that low-dose DNA demethylating agent decitabine therapy promotes CD3+ T-cell proliferation and cytotoxicity; however, direct regulation of purified CD4+ T cells and the underlying mechanisms remain unclear.MethodsThe effects of low-dose decitabine on sorted CD4+ T cells were detected both in vitro and in vivo. The activation, proliferation, intracellular cytokine production and cytolysis activity of CD4+ T cells were analyzed by FACS and DELFIA time-resolved fluorescence assays. In vivo ubiquitination assay was performed to assess protein degradation. Moreover, phosphor-p65 and IκBα levels were detected in sorted CD4+ T cells from solid tumor patients with decitabine-based therapy.ResultsLow-dose decitabine treatment promoted the proliferation and activation of sorted CD4+ T cells, with increased frequency of IFN-γ+ Th1 subset and enhanced cytolytic activity in vitro and in vivo. NF-κB inhibitor, BAY 11-7082, suppressed decitabine-induced CD4+ T cell proliferation and IFN-γ production. In terms of mechanism, low-dose decitabine augmented the expression of E3 ligase β-TrCP, promoted the ubiquitination and degradation of IκBα and resulted in NF-κB activation. Notably, we observed that in vitro low-dose decitabine treatment induced NF-κB activation in CD4+ T cells from patients with a response to decitabine-primed chemotherapy rather than those without a response.ConclusionThese data suggest that low-dose decitabine potentiates CD4+ T cell anti-tumor immunity through enhancing IκBα degradation and therefore NF-κB activation and IFN-γ production.

scholarly journals Ibrutinib Treatment Improves T-Cell Proliferative Ability and Effector Function in Relapsed/Refractory Chronic Lymphocytic Leukemia (CLL) Patients

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3114-3114
Author(s):  
Isabelle G. Solman ◽  
Marlene Taylor ◽  
Hana You ◽  
Susan M. O'Brien ◽  
Stephen P. Mulligan ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
Research Funding ◽  
T Cell Proliferation ◽  
Healthy Donors ◽  
Equity Ownership ◽  
Proliferative Ability

Abstract Background: CLL is a B-cell malignancy characterized by profound immune dysregulation, including dysfunctional T cells. Ibrutinib (ibr), a first-in-class, once-daily BTK inhibitor, is approved in the US for the treatment of CLL/SLL, and has been reported to additionally inhibit ITK in T cells. Previous studies showed that ibr has a positive impact on T-cell compartments by decreasing abnormally elevated regulatory T cells and pseudo-exhausted effector T cells, while preserving naive T-cell counts post 1 year of treatment (Solman ASH Lymphoma 2016; Solman ASCO 2017). Moreover, lower infection rates have been reported following 6 months of ibr treatment, suggesting that ibr might restore T-cell functions over time (Long JCI 2017). To further assess the effects of ibr on T-cell function, we evaluated the ability of cells to proliferate, degranulate, and release cytokines upon stimulation. Methods: Samples for this study were derived from patients (pts) with relapsed/refractory CLL enrolled in the RESONATE™ trial (Byrd NEJM 2014). In the 2 treatment arms, ibr and ofatumumab (ofa), we compared responders (PR) and non-responders (SD) per investigator assessment at week (wk) 24 - end of ofa treatment - to isolate the treatment effect on T cells. In total, we selected 19 pts wk1 through wk48 from ibr arm (420 mg once daily; 12 PR & 7 SD at wk24) and 21 pts wk1 through wk24 from ofa arm (300 mg once followed by weekly 2000 mg; 10 PR & 11 SD at wk24). Also included in the study for reference were 18 untreated, age-matched healthy donors. Cryopreserved PBMCs were immunophenotyped before and after 4-day in vitro stimulation with anti-CD3/CD28. T-cell proliferation was measured with CFSE staining, while secreted lytic proteins and cytokines were measured by bead-based immunoassays. Unless specified otherwise, median changes at wk24 relative to baseline (wk1) are reported. Results: Compared to reference range (ref) of healthy donors, all CLL samples were found to have higher percentage of apoptotic T cells. We further evaluated the fraction of apoptotic T cells in each treatment arm. In the treated CLL patients, a larger decrease in the apoptotic fraction was observed in vivo with ibr (46%) compared to ofa (24%). To evaluate how well T cells were able to respond to stimulation, we assessed T-cell death post in vitro stimulation. In vitro, both treatments were found to reduce cell death, with ofa exerting an earlier effect on apoptosis (57% for ofa vs 17% for ibr at wk24, down to 37% at wk48), and ibr having a larger effect on non-apoptotic cell death (53% for ibr at wk12-48 vs no change for ofa). T-cell proliferative ability improved significantly with ibr (+28%, P=0.001), while it decreased with ofa (-49%, P=0.003). In both arms, T-cell proliferation was higher in pts with PR compared to SD (+39% vs +6% for ibr and -20% vs -96% for ofa), and for CD8+ cells compared to CD4+ (14% for ibr and 52% for ofa). We confirmed degranulation impairment in CLL pts at baseline with a lower ability to release perforin, granzyme-A, granzyme-B, and granulysin upon stimulation. Lytic protein secretion was improved by both treatments, with a greater overall effect observed in ibr (5-fold) vs ofa pts (3-fold) at wk24. In particular, granulysin increased up to 11-fold at wk48 with ibr treatment, leading to full restoration according to ref. Relative to healthy donors, CLL pts at baseline secreted less IL-4, IL-6, IL-10, and IL-17. Each of these cytokines was increased by 3-4-fold and maintained near ref through treatment with ibr, while maximum 2-fold improvement was observed in ofa pts. IL-2 and TNF-α were elevated in CLL pts, and their secretion remained high with both treatments. Further analyses showed that degranulation and cytokine secretion changes were likely not a direct result of cell counts or disease resolution. Conclusions: Together, these data suggest ibr has a positive impact on T-cell proliferation and effector functions including degranulation and cytokine release. T-cell proliferative ability was found to be associated with treatment response, but improvement was significantly higher in ibr-treated pts, indicating a unique immune reconstitution effect of ibr beyond the effect of disease resolution. Improvement in effector T-cell function at wk24 and beyond may lead to lower infection rates in later cycles of therapy and/or support an adaptive anti-CLL immune response. Disclosures Solman: AbbVie: Equity Ownership; Pharmacyclics LLC, an AbbVie company: Employment, Other: TRAVEL, ACCOMMODATIONS, EXPENSES. Taylor:AbbVie: Equity Ownership; Pharmacyclics LLC, an AbbVie Company: Employment, Other: Travel, accomodations, expenses. You:Pharmacyclics LLC, an AbbVie Company: Employment, Other: Travel, accomodations, expenses; AbbVie: Equity Ownership. O'Brien:Acerta: Research Funding; Regeneron: Research Funding; Kite Pharma: Research Funding; Vaniam Group LLC: Consultancy; TG Therapeutics: Consultancy, Research Funding; Janssen: Consultancy; Amgen: Consultancy; Pharmacyclics: Consultancy, Research Funding; Celgene: Consultancy; Abbvie: Consultancy; Pfizer: Consultancy, Research Funding; Aptose Biosciences Inc.: Consultancy; GlaxoSmithKline: Consultancy; Astellas: Consultancy; Alexion: Consultancy; Sunesis: Consultancy, Research Funding; Gilead: Consultancy, Research Funding. Dean:CTI BioPharma Corp.: Employment, Equity Ownership; Pharmacyclics LLC, an AbbVie Company: Employment; AbbVie: Equity Ownership. James:Pharmacyclics LLC, an AbbVie Company: Employment; AbbVie: Equity Ownership, Other: Spouse's employment and stocks, Patents & Royalties: AbbVie Patent Applications. Mongan:Thermo Fisher Scientific: Patents & Royalties: Patents; AbbVie: Equity Ownership; Pharmacyclics LLC, an AbbVie Company: Employment, Other: Travel, accommodations, expenses.

Peripheral T Cell Apoptosis Is Associated with Homeostatic T Cell Proliferation and Plays a Significant Role in Post-Transplant Immune Deficiency.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 71-71
Author(s):  
Onder Alpdogan ◽  
Neel Patel ◽  
David Suh ◽  
Jeremy Grubin ◽  
Suzanne McGoldrick ◽  
...  
Keyword(s):  
Immune Deficiency ◽  
Bone Marrow ◽  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Cd8 T Cells ◽  
Cell Apoptosis ◽  
T Cell Proliferation ◽  
Post Transplant ◽  
T Cell Apoptosis

Abstract Post-transplant peripheral T cell apoptosis is an important (but ill-defined) contributor to the delay in T cell recovery after an allogeneic bone marrow transplantation (BMT). Using murine bone marrow transplantation (BMT) models to analyze post-transplant peripheral T cell apoptosis, we found that donor BM-derived T cells had a higher percentage of apoptotic cells, with decreased BCL-2 levels in young (3-month old) and old (20-month old) recipients of T cell-depleted (TCD) and T cell-repleted allogeneic BMT. Allogeneic recipients of donor BM deficient of Fas, BAX and TRAIL, or with overexpression of BCL-2 and AKT showed no decrease in donor-derived apoptotic T cells, suggesting that these molecules are not directly responsible for post-transplant peripheral T cell apoptosis. However, we noted that both CD4+ and CD8+ Memory T cells (CD44high) exhibited increased apoptosis when compared to naive T cells post-BMT and therefore used RAG-2-eGFP transgenic mice to study whether T cell maturation affects peripheral T cell apoptosis. We found increased numbers of apoptotic cells in mature (eGFPlow) T cells compared to non-divided (eGFPhigh) recent thymic emigrants in RAG-2-eGFP transgenic mice and in recipients of RAG-2-eGFP transgenic (Tg) BM. Interestingly, most of the apoptotic T cells were of eGFPlowCD44high memory phenotype in both CD4+ and CD8+ T cells, while eGFPlowCD44low naive T cells showed no sign of enhanced apoptosis. Moreover, we found similar increased levels of apoptosis of homeostatically proliferating T cells (CD44high-memory-like cells) in recipients of lineage-depleted allogeneic RAG2-eGFP Tg BM or B6 BM. We then tested the effects of homeostatic T cell proliferation on peripheral T cell apoptosis in recipients of syngeneic CFSE-labeled T cells and found again increased levels of apoptosis in the fast proliferating populations of both CD4+ and CD8+ T cells. These cells expressed high levels of CD44 but down-regulated CD62L on their surface and in contrast to allogeneic proliferation exhibited low levels of CD25 expression and high level of IL-7Rα expression (75%). In addition, BCL-2 expression was down-regulated in the fast-proliferating cell population in both CD4+ and CD8+ T cells. We conclude that newly generated donor BM-derived T cells have increased peripheral T cell apoptosis, which is associated with homeostatic proliferation and does not involve Fas, BAX, TRAIL, and AKT. This mechanism of peripheral T cell apoptosis, which has not been recognized previously, plays a significant role in post-transplant T cell deficiency and represents a promising target for novel strategies to overcome post-transplant immune deficiency in BMT recipients.

scholarly journals Siplizumab, an Anti-CD2 Monoclonal Antibody, Induces a Unique Set of Immune Modulatory Effects Compared to Alemtuzumab and Rabbit Anti-Thymocyte Globulin In Vitro

2020 ◽  
Vol 11 ◽  
Author(s):  
Christian Binder ◽  
Felix Sellberg ◽  
Filip Cvetkovski ◽  
Erik Berglund ◽  
David Berglund
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cell Activation ◽  
Mixed Lymphocyte Reaction ◽  
T Cell Proliferation ◽  
Allogeneic Mixed Lymphocyte Reaction ◽  
Dependent Cell

Antibodies are commonly used in organ transplant induction therapy and to treat autoimmune disorders. The effects of some biologics on the human immune system remain incompletely characterized and a deeper understanding of their mechanisms of action may provide useful insights for their clinical application. The goal of this study was to contrast the mechanistic properties of siplizumab with Alemtuzumab and rabbit Anti-Thymocyte Globulin (rATG). Mechanistic assay systems investigating antibody-dependent cell-mediated cytotoxicity, antibody-dependent cell phagocytosis and complement-dependent cytotoxicity were used to characterize siplizumab. Further, functional effects of siplizumab, Alemtuzumab, and rATG were investigated in allogeneic mixed lymphocyte reaction. Changes in T cell activation, T cell proliferation and frequency of naïve T cells, memory T cells and regulatory T cells induced by siplizumab, Alemtuzumab and rATG in allogeneic mixed lymphocyte reaction were assessed via flow cytometry. Siplizumab depleted T cells, decreased T cell activation, inhibited T cell proliferation and enriched naïve and bona fide regulatory T cells. Neither Alemtuzumab nor rATG induced the same combination of functional effects. The results presented in this study should be used for further in vitro and in vivo investigations that guide the clinical use of immune modulatory biologics.

scholarly journals The Role of Interleukin-10 (IL-10) in IL-15–Mediated T-Cell Responses

Blood ◽  
1997 ◽  
Vol 90 (11) ◽  
pp. 4513-4521 ◽  
Author(s):  
Dieter Körholz ◽  
Ursula Banning ◽  
Halvard Bönig ◽  
Markus Grewe ◽  
Marion Schneider ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Interleukin 10 ◽  
T Cell Proliferation ◽  
Cell Production ◽  
Cd25 Expression ◽  
Tnf Α ◽  
Ifn Γ

Abstract Interleukin-15 (IL-15) is a potent T-cell stimulating factor, which has recently been used for pre-clinical in vivo immunotherapy. Here, the IL-15 effect on CD3-stimulated peripheral human T cells was investigated. IL-15 induced a significant T-cell proliferation and upregulated CD25 expression. IL-15 significantly enhanced T-cell production of interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), and IL-10. Between 10- and 100-fold greater concentrations of IL-15 were necessary to reach a biological effect equivalent to that of IL-2. Blockade of IL-2 binding to the high-affinity IL-2 receptor did not affect the IL-15 effects, suggesting that IL-15 did not act by inducing endogenous IL-2. Exogenously administered IL-10 significantly reduced the IL-15 and IL-2–mediated IFN-γ and TNF-α production, whereas T-cell proliferation and CD25 expression were not affected. The inhibitory effects of exogenously administered IL-10 on T-cell cytokine production appeared indirect, and are likely secondary to decreased IL-12 production by accessory cells. Inhibition of endogenous IL-10 binding to the IL-10 receptor significantly increased IFN-γ and TNF-α release from T cells. These data suggest that endogenous IL-10 can regulate activated T-cell production of IFN-γ and TNF-α via a paracrine negative feedback loop. The observations of this study could be of relevance for the therapeutic use of IL-15 in vivo.

A Nanobody Against Cytotoxic T-Lymphocyte Associated Antigen-4 Increases the Anti-Tumor Effects of Specific CD8+ T Cells

2019 ◽  
Vol 15 (11) ◽  
pp. 2229-2239 ◽  
Author(s):  
Zhuoran Tang ◽  
Fengzhen Mo ◽  
Aiqun Liu ◽  
Siliang Duan ◽  
Xiaomei Yang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Tumor Cells ◽  
Cytotoxic T Lymphocyte ◽  
Ex Vivo ◽  
T Cell Proliferation ◽  
Tumor Cell Apoptosis ◽  
Xenograft Models

Adoptive cell-based immunotherapy typically utilizes cytotoxic T lymphocytes (CTLs), expanding these cells ex vivo. Such expansion is traditionally accomplished through the use of autologous APCs that are capable of interactions with T cells. However, incidental inhibitory program such as CTLA-4 pathway can impair T cell proliferation. We therefore designed a nanobody which is specific for CTLA-4 (CTLA-4 Nb 16), and we then used this molecule to assess its ability to disrupt CTLA-4 signaling and thereby overcome negative costimulation of T cells. With CTLA-4 Nb16 stimulation, dendritic cell/hepatocellular carcinoma fusion cells (DC/HepG2-FCs) enhanced autologous CD8+ T cell proliferation and production of IFN-γ in vitro, thereby leading to enhanced killing of tumor cells. Using this approach in the context of adoptive CD8+ immunotherapy led to a marked suppression of tumor growth in murine NOD/SCID hepatocarcinoma or breast cancer xenograft models. We also observed significantly increased tumor cell apoptosis, and corresponding increases in murine survival. These findings thus demonstrate that in response to nanobody stimulation, DC/tumor cells-FC-induced specific CTLs exhibit superior anti-tumor efficacy, making this a potentially valuable means of achieving better adoptive immunotherapy outcomes in cancer patients.

Glucocorticosteroids modulate antigen-induced T cell apoptosis in experimental autoimmune neuritis and cause T cell proliferation in situ

2001 ◽  
Vol 102 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Andreas Weishaupt ◽  
Lisa M. Schönrock ◽  
Martina Stienekemeier ◽  
Klaus V. Toyka ◽  
Ralf Gold
Keyword(s):  
Cell Proliferation ◽  
T Cell ◽  
Cell Apoptosis ◽  
T Cell Proliferation ◽  
Experimental Autoimmune Neuritis ◽  
T Cell Apoptosis ◽  
Experimental Autoimmune

scholarly journals Allergen-Induced C5a/C5aR1 Axis Activation in Pulmonary CD11b+ cDCs Promotes Pulmonary Tolerance through Downregulation of CD40

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 300 ◽  
Author(s):  
Konstantina Antoniou ◽  
Fanny Ender ◽  
Tillman Vollbrandt ◽  
Yves Laumonnier ◽  
Franziska Rathmann ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd4 T Cells ◽  
Cell Activation ◽  
T Cell Proliferation ◽  
C5a Receptor ◽  
The Impact

Activation of the C5/C5a/C5a receptor 1 (C5aR1) axis during allergen sensitization protects from maladaptive T cell activation. To explore the underlying regulatory mechanisms, we analyzed the impact of C5aR1 activation on pulmonary CD11b+ conventional dendritic cells (cDCs) in the context of house-dust-mite (HDM) exposure. BALB/c mice were intratracheally immunized with an HDM/ovalbumin (OVA) mixture. After 24 h, we detected two CD11b+ cDC populations that could be distinguished on the basis of C5aR1 expression. C5aR1− but not C5aR1+ cDCs strongly induced T cell proliferation of OVA-reactive transgenic CD4+ T cells after re-exposure to antigen in vitro. C5aR1− cDCs expressed higher levels of MHC-II and CD40 than their C5aR1+ counterparts, which correlated directly with a higher frequency of interactions with cognate CD4+ T cells. Priming of OVA-specific T cells by C5aR1+ cDCs could be markedly increased by in vitro blockade of C5aR1 and this was associated with increased CD40 expression. Simultaneous blockade of C5aR1 and CD40L on C5aR1+ cDCs decreased T cell proliferation. Finally, pulsing with OVA-induced C5 production and its cleavage into C5a by both populations of CD11b+ cDCs. Thus, we propose a model in which allergen-induced autocrine C5a generation and subsequent C5aR1 activation in pulmonary CD11b+ cDCs promotes tolerance towards aeroallergens through downregulation of CD40.

Donor Requirements For CD4+CD25+FoxP3+ Regulatory T Cells Capable Of Suppressing CD4+ and CD8+ Conventional T Cell Proliferation and Graft Versus Host Disease

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4484-4484 ◽  
Author(s):  
Antonio Pierini ◽  
Lucrezia Colonna ◽  
Maite Alvarez ◽  
Dominik Schneidawind ◽  
Byung-Su Kim ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Animal Models ◽  
Graft Versus Host Disease ◽  
Third Party ◽  
T Cell Proliferation ◽  
Graft Versus Host

Adoptive transfer of CD4+CD25+FoxP3+ regulatory T cells (Tregs) prevents graft versus host disease (GvHD) in several animal models and following allogeneic hematopoietic cell transplantation (HCT) in clinical trials. In these models donor derived Tregs have been mainly used as they share the same major histocompatibility complex (MHC) with conventional CD4+ and CD8+ T cells (Tcons) that are primarily responsible for GvHD onset and persistence. Third-party derived Tregs are a promising alternative tool for cellular therapy as they can be prepared in advance, screened for pathogens and activity and banked. In this study we explored MHC disparities between Tregs and Tcons in HCT to evaluate the impact of these different cell populations in GvHD prevention and survival after transplant. Methods and Results We evaluated the ability of highly purified Treg to suppress proliferation of C57BL/6 (H-2b) Tcons following exposure to irradiated splenocytes from BALB/C (H-2d) mice in vitro in a mixed lymphocyte reaction (MLR). Either donor derived C57BL/6 (H-2b) or third party FVB (H-2q) Tregs suppressed Tcon proliferation at the Treg/Tcon ratios of 1:2 and 1:4. The same Treg population effectively suppressed different MHC derived Tcons where BALB/C (H-2d) or FVB (H-2q, third-party) Tcons were incubated with irradiated splenocytes from C57BL/6 (H-2b) mice and were effectively suppressed with BALB/C (H-2d) Tregs. In the MLR, third-party Tregs present the same activation molecule expression patterns as MHC matched Tregs: CTLA4 and LAG3 expression is enhanced after stimulation with interleukin-2 (IL-2) and anti-CD3/CD28 beads, while MHC class II molecule expression is increased after 3-4 days of culture with Tcons and irradiated splenocytes. Furthermore third-party and MHC matched Tregs express the same levels of interleukin-10 (IL-10). We translated these results to in vivo studies in animal models. In these studies T cell depleted bone marrow (TCD BM) from C57BL/6 (H-2b) mice was injected into lethally irradiated (total body irradiation, 8 Gy) BALB/C (H-2d) recipient mice. 2 days later GvHD was induced by injecting luc+ donor derived Tcons (1x106/mouse). Using this model GvHD was evaluated following the adoptive transfer of freshly isolated CD4+CD25+FoxP3+ Tregs derived from BALB/C (H-2d, host type), C57BL/6 (H-2b, donor type), FVB (H-2q, third-party) or BALB/B (H-2b, minor mismatched with the donor, major mismatched with the host) mice at the different Treg/Tcon ratios of 1:1, 1:2 and 1:4. As expected, donor Tregs exerted the strongest dose dependent GvHD protection (p = 0.028), while host Tregs did not improve mouse survival (p = 0.58). Third-party and minor mismatched with the donor Tregs improved mouse survival (third-party and minor mismatched with the donor respectively, p = 0.028 and p = 0.17) but mice had worse GvHD score profiles (both p< 0.001) and could not recover their weight as well as mice treated with donor Tregs (both p< 0.001). In vivoTcon bioluminescent imaging confirmed these results showing a reduced Tcon proliferation in mice treated with donor, third-party and minor mismatched with the donor Tregs, the first exerting the strongest effect (after 6 weeks of observation, p< 0.001). Conclusions Our studies indicate that MHC disparities between Tregs and Tcons do not represent an insurmountable barrier for Treg function. In vitro and in vivo data strongly suggest that Tregs can suppress Tcon proliferation without requiring MHC matching. In vivo GvHD prevention efficiency was affected by MHC disparities with donor derived Treg being the most effective, however, third party Treg also resulted in GvHD attenuation. These studies indicate that both donor and third party Treg could be effective in clinical application raising the possibility of screening and banking Treg for use. Further, these studies highlight the need for activation of the Treg on host tissues to effectively suppress conventional T cell proliferation and GvHD induction. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Locally produced C5a binds to T cell–expressed C5aR to enhance effector T-cell expansion by limiting antigen-induced apoptosis

Blood ◽  
2008 ◽  
Vol 112 (5) ◽  
pp. 1759-1766 ◽  
Author(s):  
Peter N. Lalli ◽  
Michael G. Strainic ◽  
Min Yang ◽  
Feng Lin ◽  
M. Edward Medof ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Apoptosis ◽  
Cell Expansion ◽  
Immune Cell ◽  
Regulatory Protein ◽  
T Cell Apoptosis ◽  
T Cell Expansion

Abstract Our recent studies have shown that immune cell–produced complement provides costimulatory and survival signals to naive CD4+ T cells. Whether these signals are similarly required during effector cell expansion and what molecular pathways link locally produced complement to T-cell survival were not clarified. To address this, we stimulated monoclonal and polyclonal T cells in vitro and in vivo with antigen-presenting cells (APCs) deficient in the complement regulatory protein, decay accelerating factor (DAF), and/or the complement component C3. We found that T-cell expansion induced by DAF-deficient APCs was augmented with diminished T-cell apoptosis, whereas T-cell expansion induced by C3−/− APCs was reduced because of enhanced T-cell apoptosis. These effects were traced to locally produced C5a, which through binding to T cell–expressed C5aR, enhanced expression of Bcl-2 and prevented Fas up-regulation. The results show that C5aR signal transduction in T cells is important to allow optimal T-cell expansion, as well as to maintain naive cell viability, and does so by suppressing programmed cell death.

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