Vaccine-Induced, Pseudorabies Virus-Specific, Extrathymic CD4+CD8+ Memory T-Helper Cells in Swine

1998 ◽  
Vol 72 (6) ◽  
pp. 4866-4873 ◽  
Author(s):  
Bertram T. Ober ◽  
Artur Summerfield ◽  
Christina Mattlinger ◽  
Karl-Heinz Wiesmüller ◽  
Günther Jung ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Lymphocytes ◽  
Mhc Class Ii ◽  
T Helper Cells ◽  
Pseudorabies Virus ◽  
Class Ii ◽  
T Cell Epitopes ◽  
T Helper ◽  
Helper Cells

ABSTRACT Pseudorabies virus (PRV; suid herpesvirus 1) infection causes heavy economic losses in the pig industry. Therefore, vaccination with live attenuated viruses is practiced in many countries. This vaccination was demonstrated to induce extrathymic virus-specific memory CD4+CD8+ T lymphocytes. Due to their major histocompatibility complex (MHC) class II-restricted proliferation, it is generally believed that these T lymphocytes function as memory T-helper cells. To directly prove this hypothesis, 15-amino-acid, overlapping peptides of the viral glycoprotein gC were used for screening in proliferation assays with peripheral blood mononuclear cells of vaccinated d/d haplotype inbred pigs. In these experiments, two naturally processed T-cell epitopes (T1 and T2) which are MHC class II restricted were identified. It was shown that extrathymic CD4+CD8+ T cells are the T-lymphocyte subpopulation that responds to epitope T2. In addition, we were able to show that cytokine secretion can be induced in these T cells through recall with inactivated PRV and demonstrated that activated PRV-primed CD4+CD8+ T cells are able to induce PRV-specific immunoglobulin synthesis by PRV-primed, resting B cells. Taken together, these results demonstrate that the glycoprotein gC takes part in the priming of humoral anti-PRV memory responses. The experiments identified the first T-cell epitopes so far known to induce the generation of virus-specific CD4+CD8+ memory T lymphocytes and showed that CD4+CD8+ T cells are memory T-helper cells. Therefore, this study describes the generation of virus-specific CD4+CD8+ T cells, which is observed during vaccination, as a part of the potent humoral anti-PRV memory response induced by the vaccine.

scholarly journals Neonatal lymphocyte subpopulations analysis and maternal preterm premature rupture of membranes: a pilot study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Margherita Amadi ◽  
Silvia Visentin ◽  
Francesca Tosato ◽  
Paola Fogar ◽  
Giulia Giacomini ◽  
...  
Keyword(s):  
T Cells ◽  
Immune System ◽  
T Cell ◽  
T Helper Cells ◽  
Lymphocyte Subpopulations ◽  
T Helper ◽  
Premature Rupture Of Membranes ◽  
Premature Rupture ◽  
Preterm Premature Rupture ◽  
Helper Cells

Abstract Objectives Preterm premature rupture of membranes (pPROM) causes preterm delivery, and increases maternal T-cell response against the fetus. Fetal inflammatory response prompts maturation of the newborn’s immunocompetent cells, and could be associated with unfavorable neonatal outcome. The aims were to examine the effects of pPROM (Mercer BM. Preterm premature rupture of the membranes: current approaches to evaluation and management. Obstet Gynecol Clin N Am 2005;32:411) on the newborn’s and mother’s immune system and (Test G, Levy A, Wiznitzer A, Mazor M, Holcberg G, Zlotnik A, et al. Factors affecting the latency period in patients with preterm premature rupture of membranes (pPROM). Arch Gynecol Obstet 2011;283:707–10) to assess the predictive value of immune system changes in neonatal morbidity. Methods Mother-newborn pairs (18 mothers and 23 newborns) who experienced pPROM and controls (11 mothers and 14 newborns), were enrolled. Maternal and neonatal whole blood samples underwent flow cytometry to measure lymphocyte subpopulations. Results pPROM-newborns had fewer naïve CD4 T-cells, and more memory CD4 T-cells than control newborns. The effect was the same for increasing pPROM latency times before delivery. Gestational age and birth weight influenced maturation of the newborns’ lymphocyte subpopulations and white blood cells, notably cytotoxic T-cells, regulatory T-cells, T-helper cells (absolute count), and CD4/CD8 ratio. Among morbidities, fewer naïve CD8 T-cells were found in bronchopulmonary dysplasia (BPD) (p=0.0009), and more T-helper cells in early onset sepsis (p=0.04). Conclusions pPROM prompts maturation of the newborn’s T-cell immune system secondary to antigenic stimulation, which correlates with pPROM latency. Maternal immunity to inflammatory conditions is associated with a decrease in non-major histocompatibility complex (MHC)-restricted cytotoxic cells.

Induction and Break of Immune Tolerance to Human FVIII in a HLA-DRB1*1501 Humanized Hemophilic Mouse Model

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 2280-2280
Author(s):  
Katharina Nora Steinitz ◽  
Brigitte Binder ◽  
Christian Lubich ◽  
Rafi Uddin Ahmad ◽  
Markus Weiller ◽  
...  
Keyword(s):  
T Cells ◽  
Immune System ◽  
T Cell ◽  
Mouse Model ◽  
Mhc Class Ii ◽  
Immune Tolerance ◽  
Cd4 T Cells ◽  
Hemophilia A ◽  
Class Ii ◽  
T Cell Epitopes

Abstract Abstract 2280 Development of neutralizing antibodies against FVIII is the major complication in the treatment of patients with hemophilia A. Although several genetic and environmental risk factors have been identified, it remains unclear why some patients develop antibodies while others do not. Understanding the underlying mechanisms that drive the decision of the immune system whether or not to make antibodies against FVIII would help to design novel therapeutics. We used a new humanized hemophilic mouse model that expresses the human MHC-class II molecule HLA-DRB1*1501 on the background of a complete knock out of all murine MHC-class II genes. Initial studies had indicated that only a fraction of these mice developed antibodies when intravenously (i.v.) treated with human FVIII. These findings which resemble the situation in patients with severe hemophilia A, evoked the question if the lack of antibody development in non-responder mice reflects the induction of specific immune tolerance after i.v. application of FVIII or represent non-responsiveness for other reasons. We addressed this question by choosing another application route (subcutaneous, s.c.) and by combining i.v. application with a concomitant activation of the innate immune system applying LPS, a well characterized ligand for toll-like receptor 4, together with FVIII. Both strategies resulted in the development of antibodies in all mice included in the study what suggested that non-responsiveness against i.v. FVIII does not reflect an inability to develop antibodies against FVIII. Next, we asked if i.v. FVIII does induce immune tolerance in non-responder mice. We pretreated mice with i.v. FVIII, selected non-responder mice and challenged them with s.c. FVIII. None of the mice developed antibodies what indicated that i.v. pretreatment had induced immune tolerance in non-responder mice. Currently, we test the hypothesis that immune tolerance after i.v. application is induced and maintained by FVIII-specific regulatory T cells. The differences in responder rates after i.v. and s.c. application of FVIII raised the question if there are differences in FVIII T-cell epitopes involved in the initial activation of FVIII-specific CD4+ T cells. We obtained spleen cells from mice treated with either i.v. or s.c. FVIII and generated CD4+ T-cell hybridoma libraries that were tested for peptide specificities. For this purpose we used a FVIII peptide library containing 15 mers with an offset of 3 amino acids. Our results indicate that the pattern of FVIII-specific T-cell epitopes involved in the activation of FVIII-specific CD4+ T cells after i.v. and s.c. application of FVIII is almost identical and represents a small set of FVIII peptides distributed over the A1, A2, B, A3 and C1 domains. Based on our results we conclude that the new HLA-DRB1*1501 hemophilic mouse model represents an interesting opportunity to uncover the mechanisms that drive the decision of the immune system whether or not to develop antibodies against FVIII. Disclosures: Steinitz: Baxter BioScience: Employment. Binder:Baxter BioScience: Employment. Lubich:Baxter BioScience: Employment. Ahmad:Baxter BioScience: Employment. Weiller:Baxter BioScience: Employment. de la Rosa:Baxter BioScience: Employment. Schwarz:Baxter BioScience: Employment. Scheiflinger:Baxter BioScience: Employment. Reipert:Baxter Innovations GmbH: Employment.

scholarly journals Streptococcal Pyrogenic Exotoxin A-Stimulated Monocytes Mediate Regulatory T-Cell Accumulation through PD-L1 and Kynurenine

2019 ◽  
Vol 20 (16) ◽  
pp. 3933 ◽  
Author(s):  
Katharina Giesbrecht ◽  
Sandra Förmer ◽  
Aline Sähr ◽  
Klaus Heeg ◽  
Dagmar Hildebrand
Keyword(s):  
T Cells ◽  
Cell Death ◽  
T Cell ◽  
T Lymphocytes ◽  
Mhc Class Ii ◽  
Inflammatory Cytokines ◽  
Class Ii ◽  
Cd4 T Cell ◽  
Exotoxin A ◽  
T Effector Cells

Bacterial superantigens (SAgs) are exotoxins that promote a fulminant activation of the immune system. The subsequent intense release of inflammatory cytokines often results in hypotension, shock, and organ failure with high mortality rates. In the current paradigm, the direct and simultaneous binding of SAgs with T-cell receptor (TCR)-bearing Vβ regions and conserved structures on major histocompatibility complex class II (MHC class II) on antigen-presenting cells (APCs) induces the activation of both cell types. However, by crosslinking MHC class II molecules, APCs can be activated by SAgs independently of T lymphocytes. Recently, we showed that streptococcal pyrogenic exotoxin A (SPEA) of Streptococcus pyogenes stimulates an immunogenic APC phenotype with upregulated costimulatory molecules and inflammatory cytokines. Additionally, we revealed that SPEA triggers immunosuppressive programs in monocytes that facilitate the accumulation of regulatory T cells (Tregs) in in vitro monocyte/CD4+ T-cell cocultures. Immunosuppressive factors include anti-inflammatory interleukin 10 (IL-10), co-inhibitory surface molecule programmed cell death 1 ligand 1 (PD-L1), and the inhibitory indoleamine 2,3-dioxygenase (IDO)/kynurenine effector system. In the present study, we investigated the underlying mechanism of SPEA-stimulated monocyte-mediated accumulation of Tregs. Blood-derived monocytes from healthy donors were stimulated with SPEA for 48 h (SPEA-monocytes). For the evaluation of SPEA-monocyte-mediated modulation of CD4+ T lymphocytes, SPEA was removed from the culture through extensive washing of cells before adding allogeneic CD3/CD28-activated T cells. Results: In coculture with allogeneic CD4+ T cells, SPEA-monocytes mediate apoptosis of CD4+Foxp3− lymphocytes and accumulation of CD4+Foxp3+ Tregs. PD-L1 and kynurenine are critically involved in the mediated cell death because blocking both factors diminished apoptosis and decreased the proportion of the CD25+/Foxp3+ Treg subpopulation significantly. Upregulation of PD-L1 and kynurenine as well as SPEA-monocyte-mediated effects on T cells depend on inflammatory IL-1β. Our study shows that monocytes activated by SPEA mediate apoptosis of CD4+Foxp3− T effector cells through PD-L1 and kynurenine. CD4+Foxp3+ T cells are resistant to apoptosis and accumulate in SPEA-monocyte/CD4+ T-cell coculture.

scholarly journals Allosuppressor and allohelper T cells in acute and chronic graft-vs.-host disease. II. F1 recipients carrying mutations at H-2K and/or I-A.

1983 ◽  
Vol 157 (2) ◽  
pp. 755-771 ◽  
Author(s):  
A G Rolink ◽  
S T Pals ◽  
E Gleichmann
Keyword(s):  
T Cells ◽  
T Helper Cells ◽  
Acute Gvhd ◽  
Class Ii ◽  
Class I ◽  
T Helper ◽  
Spleen Cells ◽  
Helper Cells ◽  
Donor Cells ◽  
Donor T Cells

By induction of a graft-vs.-host reaction (GVHR) in nonirradiated H-2-different F1 mice, one can induce stimulatory pathological symptoms, such as lymphadenopathy and hypergammaglobulinemia, combined with the production of autoantibodies characteristic of systemic lupus erythematosus (SLE). Alternatively, the GVHR can lead to the suppressive pathological symptoms, such as pancytopenia and hypogammaglobulinemia, characteristic of acute GVH disease (GVHD). Whether stimulatory or suppressive symptoms are induced by a GVHR depends, in our view (2-4), on the functional subset of donor T cells activated in the F1 host. The purpose of the present study was to investigate whether class I and/or class II H-2 alloantigens can selectively trigger, out of a pool of unselected donor T cells, those subpopulations of T cells responsible for the stimulatory and suppressive GVH symptoms, respectively. For the induction of the GVHR, 10(8) lymphoid cells from C57BL/6 (B6) donors were injected into three kinds of F1 hybrid mice, which had been bred from H-2 mutant strains on a B6 background. Whereas the I-A-disparate (B6 X bm12)F1 recipients exclusively developed stimulatory GVH symptoms, including SLE-like autoantibodies and immune complex glomerulonephritis, the K locus-disparate (B6 X bm1)F1 recipients showed neither clearly stimulatory nor clearly suppressive GVH symptoms. In marked contrast, the (bm1 X bm12)F1 recipients, which differ from the B6 donor strain by mutations at both K and I-A locus, initially developed stimulatory GVH symptoms, but rapidly thereafter showed the suppressive pathological symptoms of acute GVHD and died. Moreover, spleen cells obtained from (B6 X bm12)F1 mice injected with B6 donor cells helped the primary anti-sheep erythrocyte (SRBC) response of normal (B6 X bm12)F1 spleen cells in vitro, whereas spleen cells (bm1 X bm12)F1 mice injected with B6 donor cells strongly suppressed the primary anti-SRBC response of normal (bm1 X bm12)F1 spleen cells. Spleen cells from the K locus-disparate (B6 X bm1)F1 recipients also suppressed the primary anti-SRBC of normal (B6 X bm1)F1 spleen cells; this suppression, however, was weak when compared with the suppression induced by spleen cells from GVH (bm1 X bm12)F1 mice. Taken together, these findings indicate that a small class II (I-A) antigenic difference suffices to trigger the alloreactive donor T helper cells causing SLE-like GVHD. In contrast, both class I (H-2K) and class II (I-A) differences are required to trigger the subsets of donor T cells responsible for acute GVHD. It appears that alloreactive donor T helper cells induce the alloreactive T suppressor cells, which then act as the suppressor effector cells causing the pancytopenia of acute GVHD. These findings may help to understand the variability of GVH-like diseases caused by a given etiologic agent, their cellular pathogenesis, and association with certain HLA loci.

Universally immunogenic T cell epitopes: promiscuous binding to human MHC class II and promiscuous recognition by T cells

1989 ◽  
Vol 19 (12) ◽  
pp. 2237-2242 ◽  
Author(s):  
Paola Panina-Bordignon ◽  
Agnes Tan ◽  
Annemarie Termijtelen ◽  
Stefan Demotz ◽  
Giampietro Corradin ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Mhc Class Ii ◽  
Class Ii ◽  
T Cell Epitopes

scholarly journals Tissue-resident CD4+ T helper cells assist the development of protective respiratory B and CD8+ T cell memory responses

2021 ◽  
Vol 6 (55) ◽  
pp. eabb6852
Author(s):  
Young Min Son ◽  
In Su Cheon ◽  
Yue Wu ◽  
Chaofan Li ◽  
Zheng Wang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
B Cell ◽  
T Helper Cells ◽  
Critical Role ◽  
Cell Formation ◽  
Influenza Virus Infection ◽  
T Helper ◽  
Helper Cells ◽  
Cell Immunity

Much remains unknown about the roles of CD4+ T helper cells in shaping localized memory B cell and CD8+ T cell immunity in the mucosal tissues. Here, we report that lung T helper cells provide local assistance for the optimal development of tissue-resident memory B and CD8+ T cells after the resolution of primary influenza virus infection. We have identified a population of T cells in the lung that exhibit characteristics of both follicular T helper and TRM cells, and we have termed these cells as resident helper T (TRH) cells. Optimal TRH cell formation was dependent on transcription factors involved in T follicular helper and resident memory T cell development including BCL6 and Bhlhe40. We show that TRH cells deliver local help to CD8+ T cells through IL-21–dependent mechanisms. Our data have uncovered the presence of a tissue-resident helper T cell population in the lung that plays a critical role in promoting the development of protective B cell and CD8+ T cell responses.

scholarly journals ВПЛИВ ІМУНОМОДУЛЯТОРІВ НА ПОКАЗНИКИ КЛІТИННОГО ІМУНІТЕТУ ЛОШАТ ВЕРХОВИХ ПОРІД

2016 ◽  
Vol 18 (3(71)) ◽  
pp. 45-49
Author(s):  
I.P. Кrytsia
Keyword(s):  
T Cells ◽  
Immune System ◽  
T Lymphocytes ◽  
Functional Activity ◽  
T Helper Cells ◽  
Hematological Parameters ◽  
Immune Reactivity ◽  
T Helper ◽  
Physiological Level ◽  
Helper Cells

To maintain a body at sufficient physiological level the effective functioning of the immune system, which determines the resistance and immune reactivity of animals, is necessary. In our studies in newborn foals indicators of cellular immunity were mature. During the studying of foals of all ages were established the reduction of hematological parameters in animals months of age.The use of immunomodulators prevents the immunodeficiency in animals. Immunomodulators introduction for animals normalizes T–immune system, in particular, increases the number of leucocytes in the blood, lymphocytes of certain populations, especially teofilin–resistant subpopulation of T–helper cells, increases the functional activity of lymphocytes.Under influence of ribotan revealed a trend to the increasing of T–lymphocytes by 0.2 – 1.2% (0.4 – 2.3%), respectively in Purebred Saddle and Ukrainian Saddle breeds. Results of the content of T–helper and T–suppressor cells in foals blood after ribotan administration showed that the use of immunomodulators not only increases the number of T–helper cells, but restores the ratio T–h / T–s, which returned to the optimal rate (1.9). Analyzing the functional status of T–lymphocytes during the application of immunomodulators was found the probable increase of the number of activated T–lymphocytes in Purebred Saddle foals more than 2–fold (P <0.01) and trend to increase of these cells in Ukrainian Saddle foals. In relation to thermostable T–lymphocytes, was note that the trend to the most optimal level of these cells installed in foals after administration of ribotan (values within 3 – 4%). The increasing in number of thermostable T–cells more than 4% indicates an increase power of suppressor T–cells population, indicating the inhibition of T–helper cells, and therefore the production of antibodies. Thus, the use of ribotan in dose of 1 ml / animal for three days leads to an increasing in 1.4 – 4.5% of the number of leukocytes in the blood of experimental group of foals compared with control animals. Under influence of ribotan in the blood of foals increases cell (number of T–lymphocytes in 0.4 – 2.3%) and functional activity (T–active lymphocytes in 2.3 times; P < 0.05) T–immune system. Under influence of cycloferon in the blood of foals increases the functional activity of T–immune system (the number of T–active lymphocytes in 16.7 – 25%; P < 0.05). 

scholarly journals Tissue-resident CD4+ T helper cells assist protective respiratory mucosal B and CD8+ T cell memory responses

2020 ◽  
Author(s):  
Young Min Son ◽  
In Su Cheon ◽  
Yue Wu ◽  
Chaofan Li ◽  
Zheng Wang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Helper Cells ◽  
Cell Formation ◽  
Influenza Virus Infection ◽  
T Helper ◽  
Helper Cells ◽  
Mucosal Tissues ◽  
Cell Immunity ◽  
Cd8 T Cell Memory

AbstractThe roles of CD4+ T helper cells (TH) in shaping localized memory B and CD8+ T cell immunity in the mucosal tissues are largely unexplored. Here, we report that lung TH cells provide local assistance for the optimal development of tissue-resident memory B (BRM) and CD8+ T (TRM) cells following the resolution of primary influenza virus infection. We identify a population of tissue-resident CD4+ TH (aka TRH) cells that co-exhibit follicular T helper (TFH) and TRM cell features and mediate local help of CD4+ T cells to B and CD8+ T cells. Optimal TRH cell formation requires lung B cells and transcription factors involved in TFH or TRM development. Further, we show that TRH cells deliver local help to B and CD8 T cells through CD40L and IL-21-dependent mechanisms. Our data have uncovered a new tissue-resident TH cell population that is specialized in assisting the development of mucosal protective B and CD8+ T cell responses in situ.

scholarly journals T-Cell Epitopes Shared Between Immunizing HLA and Donor HLA Associate With Graft Failure After Kidney Transplantation

2021 ◽  
Vol 12 ◽  
Author(s):  
Emma T. M. Peereboom ◽  
Benedict M. Matern ◽  
Toshihide Tomosugi ◽  
Matthias Niemann ◽  
Julia Drylewicz ◽  
...  
Keyword(s):  
Kidney Transplantation ◽  
T Cell ◽  
T Helper Cells ◽  
Graft Failure ◽  
Surrogate Marker ◽  
Kidney Graft ◽  
T Cell Epitopes ◽  
T Helper ◽  
Risk Of Death ◽  
Helper Cells

CD4+ T-helper cells play an important role in alloimmune reactions following transplantation by stimulating humoral as well as cellular responses, which might lead to failure of the allograft. CD4+ memory T-helper cells from a previous immunizing event can potentially be reactivated by exposure to HLA mismatches that share T-cell epitopes with the initial immunizing HLA. Consequently, reactivity of CD4+ memory T-helper cells toward T-cell epitopes that are shared between immunizing HLA and donor HLA could increase the risk of alloimmunity following transplantation, thus affecting transplant outcome. In this study, the amount of T-cell epitopes shared between immunizing and donor HLA was used as a surrogate marker to evaluate the effect of donor-reactive CD4+ memory T-helper cells on the 10-year risk of death-censored kidney graft failure in 190 donor/recipient combinations using the PIRCHE-II algorithm. The T-cell epitopes of the initial theoretical immunizing HLA and the donor HLA were estimated and the number of shared PIRCHE-II epitopes was calculated. We show that the natural logarithm-transformed PIRCHE-II overlap score, or Shared T-cell EPitopes (STEP) score, significantly associates with the 10-year risk of death-censored kidney graft failure, suggesting that the presence of pre-transplant donor-reactive CD4+ memory T-helper cells might be a strong indicator for the risk of graft failure following kidney transplantation.

scholarly journals Ripk3 Signaling Restricts the Development of Peripheral T Cell Lymphoma in Tet2 Deficient Mice

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3318-3318
Author(s):  
Kanak Joshi ◽  
Ryan Mack ◽  
Lei Zhang ◽  
Shanhui Liu ◽  
Mark Sellin ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Cells ◽  
T Helper Cells ◽  
Cell Lymphoma ◽  
T Cell Lymphoma ◽  
Wild Type ◽  
T Helper ◽  
Peripheral T Cell Lymphoma ◽  
Helper Cells

Abstract Inactive mutations of the Ten-eleven translocation (TET2) gene are commonly found in humans with multiple hematological malignancies including myeloproliferative neoplasm (MPN), acute myeloid leukemia, diffuse large B cell lymphoma, and peripheral T cell lymphomas (PTCL), and are frequently associated with poor prognosis and worse overall survival. TET2 mutations often occur in hematopoietic stem and progenitor cells (HSPCs) and are known to collaborate with additional mutations for full-blown malignant transformation. However, the molecular mechanism by which the disease identity is determined remains to be elucidated. Increased inflammatory cytokines are commonly detected in patients with TET2 mutations, which is associated with an increased risk of atherosclerotic cardiovascular diseases. Most Tet2 knockout (Tet2 -/-) mice develop MPN-like disease within 18 months, with only a few cases developing chronic lymphocyte leukemia-like disease at two years of age. The intestinal bacteria-induced inflammatory signaling plays a critical role in the pathogenesis of MPN-like disease in Tet2 -/- mice. Receptor-interacting protein kinase 3 (Ripk3) is a key mediator of inflammation cytokine-induced necroptosis and metabolic signaling. Compared to bone marrow (BM) cells isolated from wild-type mice, higher levels of Ripk3 activity can be detected in Tet2 -/- BM cells. To study the role of Ripk3 in Tet2 mutations associated with hematopoietic diseases, we crossed Tet2 conditional knockout (Tet2fx/fx Mx1-Cre +) mice with Ripk3 -/- mice to generate Tet2 and Ripk3 compound knockout (Tet2 -/-Ripk3 -/-) mice. Tet2 -/-Ripk3 -/- mice developed aggressive tumors by 12-15 months of age as characterized by profound hepatosplenomegaly and lymphadenopathy, with substantial lymphocytosis, neutrophilia, anemia, and thrombocytopenia. Histopathological analysis revealed an aggressive infiltration of tumor cells in the liver and spleen, and effacement of splenic follicular structures in diseased Tet2 -/-Ripk3 -/- mice. To characterize the type of malignancies, single-cell suspensions of the BM, peripheral blood (PB), and spleen from Tet2 -/-Ripk3 -/- were analyzed by flow cytometry and compared with wild-type and Tet2 -/- mice. As expected Tet2 -/- mice exhibited increased frequencies of myeloid cells in the PB, BM, and spleen. However, there was a marked expansion of CD4 + T cells in the PB, BM, and spleen of Tet2 -/-Ripk3 -/- mice. Detailed analyses of the T subsets demonstrated a marked expansion of both CD4 +PD1 +CXCR5 + follicular T helper cells (T fh) and CD4 +PD1 + peripheral T helper cells (T ph), indicating the development of a peripheral T cell lymphoma (PTCL) in the Tet2 -/-Ripk3 -/- mice. Additionally, disease characteristics including the reduced surface expression of CD3 in the tumor cells, increased levels of classical T h cytokines in the serum, as well as the presence of heterogeneous populations of cells within the tumor tissues recapitulate the pathological features of angioimmunoblastic T cell lymphoma (AITL), a subtype of PTCL. Elevated frequencies of splenic T fh and T ph cells were detected as early as 7 months of age in Tet2 -/-Ripk3 -/- mice. Such cells expressed inducible T cell costimulatory receptor (ICOS), an essential signaling mediator of the T fh development and proliferation. However, all other hematopoietic parameters including BM HSPCs and mature CD4 + T cells were comparable to wild type and single-gene Tet2 -/- mice. These results indicate that Ripk3 signaling inhibits PTCL development in Tet2 -/- mice by limiting the expansion of T fh and T ph cells. We are currently determining whether Ripk3 plays such a role by inducing necroptosis and/or restricting the differentiation of CD4 + naive T cells into peripheral T fh and T ph populations. We are also investigating whether Ripk3 signaling is inactivated in the tumor cells of human PTCL patients and whether we can treat such aggressive fatal diseases by reactivating Ripk3 signaling. Disclosures No relevant conflicts of interest to declare.

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