scholarly journals Oligoclonal Expansion of Cd8+ T Cells during Idiopathic Multicentric Castleman Disease Flares Suggests an Antigen Driven Process

Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 2411-2411
Author(s):  
Dustin Shilling ◽  
Jason E Stadanlick ◽  
Wenzhao Meng ◽  
Abhishek Rao ◽  
Vera P Krymskaya ◽  
...  

Abstract Castleman disease (CD) describes a group of heterogeneous diseases defined by shared characteristic lymph node histopathology and is classified based on the number of regions of enlarged lymph nodes. Multicentric CD (MCD) involves multiple regions of lymphadenopathy as well as systemic inflammation, cytopenias, and vital organ dysfunction due to a cytokine storm that often includes interleukin-6. In ~50% of patients, the pathogenic driver is Kaposi sarcoma-associated/human herpesvirus-8 (HHV-8) in the context of immunosuppression. In contrast, the etiologic driver in HHV8-negative MCD (idiopathic or iMCD) is unknown. To date, most research has focused on descriptive characterization of the enlarged lymph nodes, and the pathological cell types driving iMCD pathogenesis remain unidentified. Given that lymphoid cells circulate through the blood and lymph nodes, are able to produce high levels of cytokines upon activation, and are the primary cell types responsible for the enlarged lymph nodes in iMCD and other related diseases, we first performed a detailed immunophenotyping of peripheral blood mononuclear cells (PBMCs) obtained from iMCD patients in remission (n=16), iMCD patients during disease flare (n=6) and healthy donors (HD) (n=15). PBMCs were isolated by density gradient and either stained immediately or cryopreserved for future analyses. A HD sample was drawn at the same time as each experimental sample and processed and analyzed in parallel. Our initial hypothesis was that analysis of iMCD flare PBMCs would reveal an abnormal myeloid or lymphocyte subset. Thus, we stained and analyzed PBMCs for standard lineage markers: CD11b, CD15, CD19, CD3, CD56 and CD14. However, we observed no gross differences in population frequencies during either remission or flare compared to HD. Additionally, no differences in the proportions of natural killer T cells (CD3+CD56+), or CD4+ or CD8+ lymphocytes were observed. However, more refined examinations of the lymphocyte sub-sets based upon activation status revealed an increased proportion of activated memory (CD62LlowHLA-DR+) CD8+ cells during iMCD flare compared to HD and iMCD patients in remission and a decreased proportion of naïve (CD62L+CD45RA+) CD8+ cells compared to HD (p<0.05 for each comparison, Bonferroni corrected 2-tailed t-test). Interestingly, for one patient followed over a 7-month period, during which time he experienced two disease flares, the proportion of activated memory CD8+ cells mirrored the re-emergence of clinical disease symptoms, rising to 80% of all CD8+ lymphocytes during disease flare and waning as flares subsided. We next questioned whether the expansion of memory CD8+ T cells represented a diverse population of T cells with unique TCRs or alternatively, reflected the expansion of one or a few dominate TCR clones. Thus, we performed bulk TCRβ sequencing on genomic DNA from peripheral CD8+ cells obtained during the patient's partial remission between his two flares and at the start of his second disease flare (flare 2). Interestingly, we found that TCRs from CD8+ cells showed an overrepresentation of only a few clonotypes, indicating increased oligoclonality; the top 20 clones accounted for 45% (partial remission) and 52% (flare 2) of bulk CD8+ reads. Furthermore, the top copy number rearrangement comprised 7.5% (partial remission) and 10% (flare 2) of the CD8+ cell repertoires (healthy subjects' CD8+ T cell top copy number rearrangement is typically below 5%). Sequencing of activated (HLA-DR+) and memory (CD45RO+) CD8+ populations also revealed increased clonality. In these populations, the top 20 clones accounted for 45% (CD45RO+) and 33% (HLA-DR+) of sequencing reads during the patient's partial remission and increased to 61% (CD45RO+) and 54% (HLA-DR+) of sequencing reads during flare 2. Further, the top TCRβ sequences persisted over time, being identified in both the partial remission and flare 2 samples. This study identifies quantitative and phenotypic differences in CD8+ cell populations during iMCD disease flare. Furthermore, we present evidence suggesting a role for oligoclonal T cells in iMCD, as our TCRβ sequencing findings reveal a substantial accumulation of only a few TCR clonotypes in CD8+ populations during disease flare. Cumulatively, these results suggest that TCR signaling, due to antigen stimulation or T cell dysregulation may be involved in iMCD pathogenesis. Disclosures Fajgenbaum: Janssen Pharmaceuticals, Inc.: Research Funding.

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii89-ii89
Author(s):  
Subhajit Ghosh ◽  
Ran Yan ◽  
Sukrutha Thotala ◽  
Arijita Jash ◽  
Anita Mahadevan ◽  
...  

Abstract BACKGROUND Patients with glioblastoma (GBM) are treated with radiation (RT) and temozolomide (TMZ). These treatments can cause prolonged severe lymphopenia, which is associated with shorter survival. NT-I7 (efineptakin alfa) is a long-acting recombinant human IL-7 that supports the proliferation and survival CD4+ and CD8+ cells in both human and mice. We tested whether NT-I7 would protect T cells from treatment-induced lymphopenia and improve survival. METHODS C57BL/6 mice bearing intracranial tumors (GL261 or CT2A) were treated with RT (1.8 Gy/day x 5 days), TMZ (33 mg/kg/day x 5 days) and/or NT-17 (10 mg/kg on the final day of RT completion). We followed for survival and profiled CD3, CD8, CD4, FOXP3 in peripheral blood over time. In parallel, we assessed cervical lymph nodes, bone marrow, thymus, spleen, and the tumor 6 days after NT-I7 treatment. RESULTS Median survival in mice treated with NT-I7 combined with RT was significantly better than RT alone (GL261: 40d vs 34d, p&lt; 0.0021; CT2A: 90d vs 40d, p&lt; 0.0499) or NT-I7 alone (GL261: 40d vs 24d, p&lt; 0.008; CT2A: 90d vs 32d, p&lt; 0.0154). NT-17 with RT was just as effective as NT-I7 combined with RT and TMZ in both GL261 (40d vs 47d) and CT2A (90d vs 90d). NT-I7 treatment significantly increased the amount of CD8+ cells in the peripheral blood and tumor. NT- I7 rescued CD8+ T cells from RT induced lymphopenia in peripheral blood, spleen, and lymph nodes. NT-I7 alone or NT-I7 in combination with RT increased the CD8+ T cells in peripheral blood and tumor while reducing the FOXP3+ T-reg cells in the tumor microenvironment. CONCLUSIONS NT-I7 protects T-cells from RT induced lymphopenia, improves cytotoxic CD8+ T lymphocytes systemically and in the tumor, and improves survival. Presently, a phase I/II trial to evaluate NT-I7 in patients with high-grade gliomas is ongoing (NCT03687957).


2020 ◽  
Vol 8 (Suppl 3) ◽  
pp. A599-A599
Author(s):  
Subhajit Ghosh ◽  
Ran Yan ◽  
Sukrutha Thotala ◽  
Arijita Jash ◽  
Anita Mahadevan ◽  
...  

BackgroundRadiation (RT) and temozolomide (TMZ), which are standard of care for patients with glioblastoma (GBM), can cause prolonged severe lymphopenia. Lymphopenia, in turn, is an independent risk factor for shorter survival. Interleukin-7 (IL-7) is a cytokine that is required for T cell homeostasis and proliferation. IL-7 levels are inappropriately low in GBM patients with lymphopenia. NT-I7 (efineptakin alfa) is a long-acting recombinant human IL-7 that supports the proliferation and survival CD4+ and CD8+ cells in both human and mice. We tested whether NT-I7 rescues treatment-induced lymphopenia and improves survival.MethodsImmunocompetent C57BL/6 mice bearing two intracranial glioma models (GL261 and CT2A) were treated with RT (1.8 Gy/day x 5 days), TMZ (33 mg/kg/day x 5 days) and/or NT-I7 (10 mg/kg on the final day of RT completion). We profiled the CD3, CD8, CD4, FOXP3 cells in peripheral blood over time. We also immunoprofiled cervical lymph nodes, bone marrow, thymus, spleen, and the tumor 6 days after NT-I7 treatment. Survival was monitored daily.ResultsMedian survival in mice treated with NT-I7 combined with RT was significantly longer than RT alone (GL261: 40d vs 34d, p<0.0021; CT2A: 90d vs 40d, p<0.0499) or NT-I7 alone (GL261: 40d vs 24d, p<0.008; CT2A: 90d vs 32d, p<0.0154). NT-I7 with RT was just as effective as NT-I7 combined with RT and TMZ in both GL261(40d vs 47d) and CT2A (90d vs 90d). Cytotoxic CD8+ T cells were increased in both peripheral blood (0.66 x 105 to 3.34 x 105; P≤0.0001) and tumor (0.53 x 103 to 1.83 x 103; P≤0.0001) in mice treated with NT-I7 when compared to control. Similarly, NT-I7 in combination with RT increased the CD8+ T cells in peripheral blood (0.658 x 105 to 1.839 x 105 P≤0.0001) when compared to RT alone. There were decreases in tumor infiltrating FOXP3+ T-reg cells in mice treated with NT-I7 (1.9 x 104 to 0.75 x 104 P≤0.0001) and NT-I7 + RT (1.9 x 104 to 0.59 x 104 P≤0.0001) when compared to the control group without NT-I7. In addition, NT- I7 treatment increased CD8+ T cells in thymus, spleen, and lymph nodes.ConclusionsNT-I7 enhances cytotoxic CD8+ T lymphocytes systemically and in the tumor microenvironment, and improves survival. A phase I/II trial to evaluate NT-I7 in patients with high-grade gliomas is ongoing (NCT03687957).


Blood ◽  
2003 ◽  
Vol 102 (1) ◽  
pp. 180-183 ◽  
Author(s):  
Carl E. Mackewicz ◽  
Baikun Wang ◽  
Sunil Metkar ◽  
Matthew Richey ◽  
Christopher J. Froelich ◽  
...  

Abstract In HIV infection, CD8+ cells show cytotoxic and noncytotoxic anti-HIV activity. The latter function is mediated, at least in part, by a secreted antiviral protein, the CD8+ cell antiviral factor (CAF). Because antiviral effector molecules, such as perforin and granzymes, reside in the exocytic granules of CD8+ T cells, we examined the possibility that granules contain CAF-like activity. CD8+ cells from HIV-infected individuals showing strong CAF-mediated antiviral activity were induced to release their granule constituents into culture media. Within 1 hour of stimulation, high levels of granzyme B (a primary granule constituent) were found in the culture fluids of previously activated CD8+ cells. The same culture fluids contained no or very low amounts of CAF activity, as measured with HIV-infected CD4+ cells. Maximal levels of CAF activity were not observed until 5 or 7 days after stimulation, consistent with typical CAF production kinetics. In addition, extracts of granules purified from antiviral CD8+ cells did not show any CAF activity, whereas the cytoplasmic fraction of these cells showed substantial levels of antiviral activity. These findings suggest that CAF does not reside at appreciable levels in the exocytic granules of antiviral CD8+ T cells. (Blood. 2003;102: 180-183)


2017 ◽  
Vol 1 (S1) ◽  
pp. 62-63
Author(s):  
Robyn Gartrell ◽  
Douglas Marks ◽  
Thomas Hart ◽  
Yan Lu ◽  
Ed Stack ◽  
...  

OBJECTIVES/SPECIFIC AIMS: Precise biomarkers are urgently needed to characterize the tumor immune microenvironment in primary melanoma tumors both for prognostication and to predict the benefit of immuno-therapeutic intervention. The goal of this work is to define spatial relationships between CD8+ T cells, CD68+ macrophages and Sox10+ melanoma cells in order to define features correlating with prolonged survival METHODS/STUDY POPULATION: Five micrometer slides from either the primary biopsy or subsequent wide local excision procedure were stained using Opal multiplex IHC for DAPI, CD3 (LN10, Leica), CD8 (4B11, Leica), CD68 (KP1, Biogenex), SOX10 (BC34, Biocare), HLA-DR (LN-3, Abcam), and Ki67 (MIB1, Abcam). Cell phenotypes within representative fields preselected by a trained dermato-pathologist and were visualized using the Mantra quantitative pathology workstation (PerkinElmer), and analysis of spatial distribution of CD3+ CD8+ cells analyzed using inForm® image analysis software (PerkinElmer), and Spotfire software (TIBCO). In order to test whether mIHC can better characterize the tumor immune microenvironment, we screened databases at the Herbert Irving Cancer Center (HICC) at Columbia University for stage II/III melanoma patients diagnosed between 2000 and 2012, with available FFPE of primary melanoma tissue and documented clinical follow-up. We identified a preliminary population of 57 patients to begin our analysis. Clinical follow-up was available on 35 patients of whom 21 patients were alive with no evidence of recurrence or died with no evidence of recurrence and 14 had died of melanoma. Twenty-four patients had more than 24 months of survival information available but no detailed clinical information to determine cause of death. RESULTS/ANTICIPATED RESULTS: First, we evaluated whether density of immune cells in tumor and stroma predicted prognosis in 35 patients with disease specific survival information. We find that high number of CD3+CD8+ cells in tumor correlates with Disease Specific Survival (DSS) (p=0.0323*) and CD3+CD8+ cells in stroma may also correlate with DSS (p=0.0671). This is consistent with what is known in the literature regarding tumor infiltrating lymphocytes (TILs). We also found that CD68+ cells in stroma predict poor prognosis (0.0259*). This is consist with the proposed deleterious role for macrophages in tumor progression. Next, using nearest neighbor analysis we examined the effect of HLA-DR and Ki67 expression on spatial distribution of CD3+CD8+ T cells. We find that CD8+ T cells are closer to myeloid (CD68+) cells expressing HLA-DR. This is consistent with the potential of HLA-DR expressing cells to present antigens to T cells, and suggests that T cells may preferentially interact with HLA-DR expressing myeloid cells. Conversely, we find that Ki67 expression on tumor (SOX10+) cells correlates with increased distance from CD3+CD8+ T cells relative to SOX10+Ki67-tumor cells. This finding is consistent with the observation that more advanced tumors with higher mitotic rates have decreased T cell infiltrates, and suggests that dividing melanoma cells are less likely to interact with T cells. In addition, we performed analysis to determine whether spatial relationships defined above impact prognosis. Clinical oncology follow-up was available on 35 of the 57 patients evaluated above. We compared proximity of CD3+CD8+ cells to both myeloid (CD68+) and tumor (SOX10+) cells in patients who recurred and those with no evidence of recurrence. We found that CD3+CD8+ cells in patients who had recurrence were closer to CD68+ HLA-DR− cells than in patients who had no recurrence (t-test, p=0.0377), this correlated with DSS (p=0.003). Conversely, distance from CD3+CD8+ to CD68+ HLA-DR+ in relationship to recurrence was not significant with a trend towards CD3+CD8+ T cells being closer in nonrecurrent patients (t-test, p=0.1362). DISCUSSION/SIGNIFICANCE OF IMPACT: Consistent with the literature, we find that densities of CD8+ T cells correlates with favorable outcomes in early stage melanoma. We also find that density of CD68+ macrophages in stroma correlates with poor outcome. If proximity is a surrogate for interaction, these data indicate that dividing, Ki67+, melanoma cells interact less with CD8+ T cells than do Ki67+ melanoma cells. Further, HLA-DR expression on CD68+ infiltrating cells likely enhances their interaction with T cells. Interestingly, on further analysis, CD3+CD8+ cells were significantly closer to CD68+ HLA-DR− cells in patients who recurred, implying that interactions between these cell types may not be favorable. This analysis demonstrates that spatial analysis may be useful in predicting prognosis in early stage melanoma, and this is the first report of this type of analysis predicting outcomes in primary tumor specimens to our knowledge. Further staining and analysis of the complete patient cohort (n=120) is ongoing.


Blood ◽  
1993 ◽  
Vol 82 (5) ◽  
pp. 1546-1552 ◽  
Author(s):  
P Sala ◽  
E Tonutti ◽  
C Feruglio ◽  
F Florian ◽  
A Colombatti

Abstract CD4+ CD8+ cells are present during T cell differentiation in the thymus. Less than 2% of normal T cells that coexpress CD4 and CD8 also are released in the circulation and are present in the peripheral blood. In this study, nine individuals are described that manifested persistent expansions (11% to 43%) of circulating CD4+ CD8+ T cells that in three cases had large granular lymphocyte (LGL) morphology in the absence of either lymphocytosis or overt lymphoproliferative disorders. Southern blot hybridization of enriched CD4+ CD8+ cells with T-cell receptor beta (TCR beta) and TCR gamma probes showed that most cases had the 12-kb Eco RI germinal band deleted or of decreased intensity. In several individuals new TCR beta-specific bands of different intensity and distinct from case to case suggested either monoclonal or oligoclonal and polyclonal expansions. Immunophenotypic analysis showed that in 7 out of 9 cases the CD4+ CD8+ T cells presented with CD8 dim expression. Furthermore, all the CD4+ CD8+ cells did not express many of the known activation antigens (low or absent CD25, CD38, CD71, HLA-DR), whereas they expressed high levels of CD2, CD29, CD56, and CD57. In addition, the CD4+ CD8+ cells of 5 out of 9 subjects coexpressed CD45RA and CD45RO suggesting that these cells might be “frozen” in an intermediate state between naive and memory T cells. In conclusion, the present CD4+ CD8+ cases fall within a larger spectrum of disorders ranging from apparently normal to reactive or proliferative situations and encompassing cells with LGL morphology or LGL-associated antigens expression either in the presence or in the absence of absolute lymphocytosis that deserve careful follow-up investigations.


Blood ◽  
1993 ◽  
Vol 82 (5) ◽  
pp. 1546-1552 ◽  
Author(s):  
P Sala ◽  
E Tonutti ◽  
C Feruglio ◽  
F Florian ◽  
A Colombatti

CD4+ CD8+ cells are present during T cell differentiation in the thymus. Less than 2% of normal T cells that coexpress CD4 and CD8 also are released in the circulation and are present in the peripheral blood. In this study, nine individuals are described that manifested persistent expansions (11% to 43%) of circulating CD4+ CD8+ T cells that in three cases had large granular lymphocyte (LGL) morphology in the absence of either lymphocytosis or overt lymphoproliferative disorders. Southern blot hybridization of enriched CD4+ CD8+ cells with T-cell receptor beta (TCR beta) and TCR gamma probes showed that most cases had the 12-kb Eco RI germinal band deleted or of decreased intensity. In several individuals new TCR beta-specific bands of different intensity and distinct from case to case suggested either monoclonal or oligoclonal and polyclonal expansions. Immunophenotypic analysis showed that in 7 out of 9 cases the CD4+ CD8+ T cells presented with CD8 dim expression. Furthermore, all the CD4+ CD8+ cells did not express many of the known activation antigens (low or absent CD25, CD38, CD71, HLA-DR), whereas they expressed high levels of CD2, CD29, CD56, and CD57. In addition, the CD4+ CD8+ cells of 5 out of 9 subjects coexpressed CD45RA and CD45RO suggesting that these cells might be “frozen” in an intermediate state between naive and memory T cells. In conclusion, the present CD4+ CD8+ cases fall within a larger spectrum of disorders ranging from apparently normal to reactive or proliferative situations and encompassing cells with LGL morphology or LGL-associated antigens expression either in the presence or in the absence of absolute lymphocytosis that deserve careful follow-up investigations.


Blood ◽  
2018 ◽  
Vol 132 (Supplement 1) ◽  
pp. 3334-3334 ◽  
Author(s):  
Dong Hoon Lee ◽  
Francisco Cervantes-Contreras ◽  
Sang Yun Lee ◽  
Damian J. Green ◽  
Brian G. Till

Abstract BACKGROUND: Current manufacturing paradigms for chimeric antigen receptor (CAR) modified T cells require ex vivo T cell activation, genetic modification, and expansion in cytokine-containing cell cultures. Most CAR T cell studies infuse cell products generated from unselected cells, in which the CD4:CD8 ratio is determined by what is collected during leukapheresis. The proportion of each subset can vary greatly in these products, reflecting the high heterogeneity of the CD4:CD8 ratio present in patients' (pts) blood at the time of treatment. Preclinical data demonstrate superior in vivo anti-tumor efficacy of cell products consisting of equal numbers of CD4+ and CD8+ T cells, and a recent clinical trial, in which CD19-targeted CAR T cell products were infused at a 1:1 ratio of CD4:CD8 T cells, showed clear dose-response and dose-toxicity relationships. However, CAR T cell manufacturing using parallel CD4+ and CD8+ CAR T cell cultures adds significant cost and complexity compared with a single-stream culture. Additionally, we have found that CD8+ T cell cultures from heavily treated pts often exhibit suboptimal expansion. We therefore evaluated whether CAR T cell products with approximately equal ratios of CD4+ to CD8+ cells could be generated by mixing CD4+ and CD8+ cells at a defined ratio at culture initiation, and whether the presence of ex vivo CD4+ help can improve CD8+ cell expansion. METHODS: CD4+ and CD8+ T cells were isolated from apheresis peripheral blood mononuclear cell products of lymphoma pts (n=15) treated in one of three CD20-targeted CAR T cell trials or healthy donors (n=5) using positive (CD4) and negative (CD8) immunomagnetic bead selection. Cell cultures (1x106 cells each) were established by activating CD4+ and CD8+ cells with anti-CD3/CD28-coated paramagnetic beads, mixing them at various ratios in 24-well plates, and transducing 24 hours later with a lentivirus encoding the 1.5.3-NQ-28-BB-z CD20 CAR. Beads were removed at day 4, and cells were expanded in IL-2 containing medium. At day 7, cells were counted and analyzed by flow cytometry for CD4, CD8, and CAR expression, and then restimulated 1:1 with irradiated CD20+ lymphoblastoid cells to boost growth. On day 14 cells were again counted and analyzed by flow cytometry for CD4, CD8, and CAR expression, as well as immunophenotype. In some cases CAR+CD4+ and CAR+CD8+ cells were flow-sorted from either CD4-only, CD8-only, and mixed cultures, stained with CFSE, and restimulated with irradiated CD20+ Raji tumor cells. Proliferation and cytokine secretion were measured by flow cytometry and Luminex, respectively. In vivo T cell activity was assessed using an NSG mouse model in which T cells were infused 7 days after i.v. injection of Raji-ffLuc cells. Suboptimal doses of T cells were used to distinguish differences between conditions, since higher doses cure most mice. Mice received either: (1) 70:30 mixed CD4:CD8 CAR+ cultures (n=8), (2) 1:1 ratio of CD4:CD8 CAR+ cells grown separately (n=8), (3) Mixed CD4:CD8 empty vector cells (n=5), or (4) no treatment (n=5). RESULTS: An initial CD4:CD8 ratio of 70:30 yielded a median CD4/CD8 ratio of 1.1 for pts (Figure 1A) and 1.3 for donors at day 7, and a ratio of 0.6 and 1.0 for pts and donors, respectively, at day 14. Mixed cultures resulted in CD8+ cell expansion that was significantly higher than in separate cultures. At day 7, mean CD8+ cell expansion was 12.1-fold vs. 4.6-fold for 70:30 mixed vs. separate cultures for donors, and 2.9-fold vs. 0.7-fold for pts (Figure 1B). At day 14 CD8+ mean cell expansion was 105-fold (70:30 mixed) vs. 25-fold (separate) for donors and 40-fold vs. 1.9-fold for pts. CD8+ cells grown in mixed cultures also exhibited higher expression of memory markers (CD62L and CCR7), lower levels of exhaustion markers (Lag-3 and PD-1), and better proliferation compared with CD8 cells grown in separate cultures. In the mice we found that tumor growth inhibition was superior in the 70:30 mixed culture group than in mice receiving a 1:1 ratio of CD4:CD8 cells grown separately (Figure 1C). CONCLUSIONS: A single-stream CAR T cell culture initiated at a defined CD4:CD8 ratio of 70:30 yielded on average approximately equal numbers of CD4+ and CD8+ cells in the final cell product. Mixed CD4+ and CD8+ cultures generated CD8+ T cells with a less differentiated phenotype, and superior expansion, proliferative capacity, and in vivo activity compared with CD4+ and CD8+ cells manufactured in parallel. Disclosures Green: Juno Therapeutics: Patents & Royalties, Research Funding. Till:Mustang Bio: Patents & Royalties, Research Funding.


2002 ◽  
Vol 197 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Melanie S. Vacchio ◽  
Richard J. Hodes

Whereas ligation of CD28 is known to provide a critical costimulatory signal for activation of CD4 T cells, the requirement for CD28 as a costimulatory signal during activation of CD8 cells is less well defined. Even less is known about the involvement of CD28 signals during peripheral tolerance induction in CD8 T cells. In this study, comparison of T cell responses from CD28-deficient and CD28 wild-type H-Y–specific T cell receptor transgenic mice reveals that CD8 cells can proliferate, secrete cytokines, and generate cytotoxic T lymphocytes efficiently in the absence of CD28 costimulation in vitro. Surprisingly, using pregnancy as a model to study the H-Y–specific response of maternal T cells in the presence or absence of CD28 costimulation in vivo, it was found that peripheral tolerance does not occur in CD28KO pregnants in contrast to the partial clonal deletion and hyporesponsiveness of remaining T cells observed in CD28WT pregnants. These data demonstrate for the first time that CD28 is critical for tolerance induction of CD8 T cells, contrasting markedly with CD28 independence of in vitro activation, and suggest that the role of CD28/B7 interactions in peripheral tolerance of CD8 T cells may differ significantly from that of CD4 T cells.


Author(s):  
Mohammad H. Rashid ◽  
Thaiz F. Borin ◽  
Roxan Ara ◽  
Raziye Piranlioglu ◽  
Bhagelu R. Achyut ◽  
...  

AbstractMyeloid-derived suppressor cells (MDSCs) are an indispensable component of the tumor microenvironment (TME), and our perception regarding the role of MDSCs in tumor promotion is attaining extra layer of intricacy in every study. In conjunction with MDSC’s immunosuppressive and anti-tumor immunity, they candidly facilitate tumor growth, differentiation, and metastasis in several ways that yet to be explored. Alike any other cell types, MDSCs also release a tremendous amount of exosomes or nanovesicles of endosomal origin and partake in intercellular communications by dispatching biological macromolecules. There has not been any experimental study done to characterize the role of MDSCs derived exosomes (MDSC exo) in the modulation of TME. In this study, we isolated MDSC exo and demonstrated that they carry a significant amount of proteins that play an indispensable role in tumor growth, invasion, angiogenesis, and immunomodulation. We observed higher yield and more substantial immunosuppressive potential of exosomes isolated from MDSCs in the primary tumor area than those are in the spleen or bone marrow. Our in vitro data suggest that MDSC exo are capable of hyper activating or exhausting CD8 T-cells and induce reactive oxygen species production that elicits activation-induced cell death. We confirmed the depletion of CD8 T-cells in vivo by treating the mice with MDSC exo. We also observed a reduction in pro-inflammatory M1-macrophages in the spleen of those animals. Our results indicate that immunosuppressive and tumor-promoting functions of MDSC are also implemented by MDSC-derived exosomes which would open up a new avenue of MDSC research and MDSC-targeted therapy.


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