scholarly journals PD-1 dependent expansion of Amphregulin+FOXP3+ cells is associated with oral immune dysfunction in HIV patients on therapy

2021 ◽  
Author(s):  
N Bhaskaran ◽  
E Schneider ◽  
F Faddoul ◽  
A Paes da Silva ◽  
R Asaad ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Oral Mucosa ◽  
Immune Dysfunction ◽  
People Living With Hiv ◽  
Dependent Manner ◽  
Mucosal Tissues ◽  
T Cell Regulation ◽  
Ifn Γ

AbstractResidual systemic inflammation and mucosal immune dysfunction persist in people living with HIV (PLWH) despite treatment with combined anti-retroviral therapy (cART), but the underlying immune mechanisms are poorly understood. Here we report an altered immune landscape involving upregulation of TLR- and inflammasome signaling, localized CD4+ T cell hyperactivation, and counterintuitively, an enrichment of CD4+CD25+FOXP3+ regulatory T cells (Tregs) in the oral mucosa of HIV+ patients on therapy. Using human oral tonsil cultures, we found that HIV infection causes an increase in a unique population of FOXP3+ cells expressing PD-1, IFN-γ, Amphiregulin (AREG), and IL-10. These cells persisted even in the presence of the anti-retroviral drug and underwent further expansion driven by TLR-2 ligands and IL-1β. IL-1β also promoted PD-1 upregulation in AKT1 dependent manner. PD-1 stabilized FOXP3 and AREG expression in these cells through a mechanism requiring the activation of Asparaginyl Endopeptidase (AEP). Importantly, these FOXP3+ cells were incapable of suppressing CD4+ T cells in vitro. Concurrently, HIV+ patients harbored higher levels of PD-1, IFN-γ, Amphiregulin (AREG), and IL-10 expressing FOXP3+ cells, which strongly correlated with CD4+ T cell hyperactivation, suggesting an absence of CD4+ T cell regulation in the oral mucosa. Taken together, this study provides insights into a novel mechanism of FOXP3+ cell dysregulation and reveals a critical link in the positive feedback loop of oral mucosal immune activation events in HIV+ patients on therapy.One Sentence SummaryHIV-induced immune dysfunction in lymphoid and mucosal tissues

scholarly journals Oral immune dysfunction is associated with the expansion of FOXP3+PD-1+Amphiregulin+ T cells during HIV infection

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
N. Bhaskaran ◽  
E. Schneider ◽  
F. Faddoul ◽  
A. Paes da Silva ◽  
R. Asaad ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Hiv Infection ◽  
Immune Dysfunction ◽  
Hiv Positive ◽  
People Living With Hiv ◽  
Asparaginyl Endopeptidase ◽  
Ifn Γ ◽  
Living With Hiv

AbstractResidual systemic inflammation and mucosal immune dysfunction persist in people living with HIV, despite treatment with combined anti-retroviral therapy, but the underlying immune mechanisms are poorly understood. Here we report that the altered immune landscape of the oral mucosa of HIV-positive patients on therapy involves increased TLR and inflammasome signaling, localized CD4+ T cell hyperactivation, and, counterintuitively, enrichment of FOXP3+ T cells. HIV infection of oral tonsil cultures in vitro causes an increase in FOXP3+ T cells expressing PD-1, IFN-γ, Amphiregulin and IL-10. These cells persist even in the presence of anti-retroviral drugs, and further expand when stimulated by TLR2 ligands and IL-1β. Mechanistically, IL-1β upregulates PD-1 expression via AKT signaling, and PD-1 stabilizes FOXP3 and Amphiregulin through a mechanism involving asparaginyl endopeptidase, resulting in FOXP3+ cells that are incapable of suppressing CD4+ T cells in vitro. The FOXP3+ T cells that are abundant in HIV-positive patients are phenotypically similar to the in vitro cultured, HIV-responsive FOXP3+ T cells, and their presence strongly correlates with CD4+ T cell hyper-activation. This suggests that FOXP3+ T cell dysregulation might play a role in the mucosal immune dysfunction of HIV patients on therapy.

scholarly journals Dual blockade of IL-6 and CTLA-4 regresses pancreatic tumors in a CD4+ T cell-dependent manner

2020 ◽  
Author(s):  
Michael Brandon Ware ◽  
Christopher McQuinn ◽  
Mohammad Y. Zaidi ◽  
Hannah Knochelmann ◽  
Thomas A. Mace ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
T Cells ◽  
T Cell ◽  
Pancreatic Tumors ◽  
Dependent Manner ◽  
Checkpoint Inhibition ◽  
Immune Checkpoint Inhibition ◽  
Dual Blockade ◽  
Ifn Γ

AbstractPancreatic ductal adenocarcinoma (PDAC) is exceptionally resistant to immune checkpoint inhibition (ICI). We previously reported that elevated systemic interleukin-6 (IL-6) and increased numbers of T cells positive for circulating cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) correlate with worse overall survival in patients with PDAC. We postulated that combined blockade of IL-6 and CTLA-4 would significantly enhance anti-tumor immune responses to PDAC. Dual blockade of IL-6 and CTLA-4 in immune competent mice bearing subcutaneously injected pancreatic tumors significantly inhibited tumor growth, accompanied by overwhelming T cell infiltration. Therapeutic efficacy was confirmed in an orthotopic murine model of pancreatic cancer and T cell depletion studies unveiled a unique dependence on CD4+ T cells for anti-tumor activity of dual IL-6 and CTLA-4 blockade. In vitro studies utilizing T cells from a TRP-1 transgenic mouse as an antigen-specific model system demonstrate this combination therapy elicits increased IFN-γ production by activated CD4+ T cells. Additionally, IFN-γ stimulation of pancreatic tumor cells in vitro profoundly increased tumor cell production of CXCR3 specific chemokines (CXCL10 and CXCL9). Further studies blocking CXCR3 in the presence of combined IL-6 and CTLA-4 blockade prevented orthotopic tumor regression, demonstrating a dependence on the CXCR3 axis for anti-tumor efficacy. We also found combination therapy increased intratumoral CD4+ T cells and elicited systemic changes in T-helper subsets. These data represent the first report of IL-6 and CTLA-4 blockade as a means to regress pancreatic tumors with defined operative mechanisms of efficacy. Given these results, this therapeutic combination has potential for immediate clinical translation.One Sentence SummaryBlockade of interleukin-6 in pancreatic cancer enhances CTLA-4 immune checkpoint inhibition to regress tumors in a CD4+ T cell and CXCR3-dependent manner.

scholarly journals Gamma Interferon Production, but Not Perforin-Mediated Cytolytic Activity, of T Cells Is Required for Prevention of Toxoplasmic Encephalitis in BALB/c Mice Genetically Resistant to the Disease

2004 ◽  
Vol 72 (8) ◽  
pp. 4432-4438 ◽  
Author(s):  
Xisheng Wang ◽  
Hoil Kang ◽  
Takane Kikuchi ◽  
Yasuhiro Suzuki
Keyword(s):  
T Cells ◽  
T Cell ◽  
Nude Mice ◽  
Genetic Resistance ◽  
Cytolytic Activity ◽  
Gamma Interferon ◽  
Toxoplasmic Encephalitis ◽  
Wild Type ◽  
Ifn Γ

ABSTRACT We previously showed the requirement of both T cells and gamma interferon (IFN-γ)-producing non-T cells for the genetic resistance of BALB/c mice to the development of toxoplasmic encephalitis (TE). In order to define the role of IFN-γ production and the perforin-mediated cytotoxicity of T cells in this resistance, we obtained immune T cells from spleens of infected IFN-γ knockout (IFN-γ−/−), perforin knockout (PO), and wild-type BALB/c mice and transferred them into infected and sulfadiazine-treated athymic nude mice, which lack T cells but have IFN-γ-producing non-T cells. Control nude mice that had not received any T cells developed severe TE and died after discontinuation of sulfadiazine treatment due to the reactivation of infection. Animals that had received immune T cells from either wild-type or PO mice did not develop TE and survived. In contrast, nude mice that had received immune T cells from IFN-γ−/− mice developed severe TE and died as early as control nude mice. T cells obtained from the spleens of animals that had received either PO or wild-type T cells produced large amounts of IFN-γ after stimulation with Toxoplasma gondii antigens in vitro. In addition, the amounts of IFN-γ mRNA expressed in the brains of PO T-cell recipients did not differ from those in wild-type T-cell recipients. Furthermore, PO mice did not develop TE after infection, and their IFN-γ production was equivalent to or higher than that of wild-type animals. These results indicate that IFN-γ production, but not perforin-mediated cytotoxic activity, by T cells is required for the prevention of TE in genetically resistant BALB/c mice.

scholarly journals 323 Immunogenic syngeneic model MC38-OVA for the preclinical evaluation of immune evasion and checkpoint blockade

2021 ◽  
Vol 9 (Suppl 3) ◽  
pp. A348-A348
Author(s):  
Jessie Wang ◽  
Kaixia Lian ◽  
Jia Zheng ◽  
Chenpan Nie ◽  
Annie An ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Tumor Immunity ◽  
Immune Evasion ◽  
Syngeneic Mouse ◽  
Ifn Γ ◽  
Draining Lymph Nodes ◽  
Syngeneic Tumors

BackgroundThe development of immuno-oncology (I/O) therapeutics has revolutionized the cancer treatment landscape. Despite this achievement, the mechanism behind limited responses is poorly understood. Tumor immune evasion has been reported to arise through the loss of tumor necrosis factor (TNF) signaling, interferon-γ (IFN-γ) signaling, and antigen presentation pathways, which are crucial to CD8+ T cell-mediated killing. Syngeneic mouse models have been widely used as they have an intact immune system, are easily accessible, and have a vast array of historical data for comparison. However, limited syngeneic models respond to immune checkpoint inhibitors, possibly due to low intrinsic immunogenicity. The expression of ovalbumin (OVA) has previously shown to sufficiently alter the susceptibility of syngeneic tumors to host T cell-mediated responses. In this study, the newly developed OVA-expressing MC38 syngeneic line was characterized for tumor immunity, checkpoint blockade response and response durability.MethodsMurine colon cancer MC38 cells were transduced by lentiviral vector with chicken OVA coding cDNA. A single clone was selected, and OVA expression was confirmed by western blot. The MC38-OVA cells were subcutaneously implanted into immunocompetent mice to evaluate the tumorigenicity and in vivo response to anti-PD-1 antibody treatment. Blood was collected 2 days post final dose of anti-PD-1 treatment for phenotypic analysis by FACS. Spleen and tumor draining lymph nodes were collected at termination for FACS analysis of IFN-γ+ T cells and OVA specific CD8+ T cells. Adoptive transfer was evaluated by challenge studies in both MC38-OVA and MC38 tumor-bearing mice with T cells derived from MC38-OVA mice, anti-PD-1 cured mice and OT-I mice. In vitro killing assays were performed to evaluate the function of adoptive CD3+ T cells transfer.ResultsOVA-expressing MC38 presented complete regression under anti-PD-1 treatment in vivo. T cell expansion was observed after anti-PD-1 treatment in peripheral blood with increased IFN-γ+ T cells in both tumor-draining lymph nodes and spleen. Additionally, anti-PD-1 cured mice generated robust tumor specific memory T cell, which successfully inhibited MC38-OVA and MC38 tumor growth following adoptive transfer. CD3+ T cells from MC38-OVA-bearing mice and OT-I mice showed anti-tumor immunity in vivo. In vitro killing assay demonstrated increased immunity.ConclusionsSyngeneic mouse tumor models are preferred preclinical models for I/O research, despite limited intrinsic immunogenicity. OVA expression in syngeneic tumors largely increased T cell-mediated immunity to enhance antigen-specific T cell responses during tumorigenesis, providing novel immunogenic models for preclinical immunotherapy evaluation.

scholarly journals Sunitinib Exerts In Vitro Immunomodulatory Activity on Sarcomas via Dendritic Cells and Synergizes With PD-1 Blockade

2021 ◽  
Vol 12 ◽  
Author(s):  
Darina Ocadlikova ◽  
Mariangela Lecciso ◽  
Javier Martin Broto ◽  
Katia Scotlandi ◽  
Michele Cavo ◽  
...  
Keyword(s):  
Flow Cytometry ◽  
T Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Cell Lines ◽  
Effector T Cells ◽  
Sarcoma Cell ◽  
Ifn Γ ◽  
Sarcoma Cells

BackgroundHigh-grade sarcomas are a heterogeneous group of aggressive tumors arising in bone and soft tissues. After relapse, treatment options are limited. The multi-targeted receptor tyrosine kinase inhibitors (TKIs) sunitinib and inhibitor of PD-1 (anti-PD-1) nivolumab have shown antitumor activity in selected subtypes. In this study, we examine the role of TKIs and PD-1 based therapy in in vitro cocultures of sarcoma.MethodsThe human osteosarcoma (SaOS-2) and synovial sarcoma (SYO-1) cell lines were treated with sunitinib. After cell death and proliferation assessment, expression of PD-L1 was analyzed by flow cytometry. Sunitinib-treated sarcoma cells were cocultured with dendritic cells (DCs), and the phenotype of mature DCs was determined by flow cytometry. Mature DCs were cultured with autologous T cells. PD-1 expression on T cells, their proliferation, T regulatory cell (Tregs) induction and IFN-γ production, before and after nivolumab exposure, were analyzed.ResultsAlong with its anti-proliferative and direct pro-apoptotic effect on sarcoma cell lines, sunitinib prompted PD-L1 upregulation on sarcoma cells. Interestingly, sunitinib-treated sarcoma cells drive DCs to full maturation and increase their capacity to induce sarcoma-reactive T cells to produce IFN-γ. Conversely, no effect on T cell proliferation and T cell subpopulation composition was observed. Moreover, both bone and synovial sarcoma cell lines induced Tregs through DCs but sunitinib treatment completely abrogated Treg induction. Finally, sarcoma cell lines induced PD-1 upregulation on both effector T cells and Tregs when loaded into DCs, providing a rationale for using PD-1 blockade. Indeed, PD-1 blockade by nivolumab synergized with sunitinib in inducing IFN-γ-producing effector T cells.ConclusionsTaken together, our in vitro data indicate that the treatment of sarcoma cells with sunitinib can exert significant changes on immune cell subsets toward immune activation, leading to DC-based cross-priming of IFN-γ-producing effector T cells and reduced Treg induction. PD-1 blockade with nivolumab has a synergistic effect with sunitinib, supporting the use of TKI and anti-PD-1 approach in sarcomas, and perhaps in other cancers. DC-targeted drugs, including toll-like receptor 3 inhibitors and CD47 inhibitors, are under development and our preclinical model might help to better design their clinical application.

scholarly journals An Ex Vivo Study of T Lymphocytes Recovered from the Lungs of I/St Mice Infected with and Susceptible toMycobacterium tuberculosis

1998 ◽  
Vol 66 (10) ◽  
pp. 4981-4988 ◽  
Author(s):  
Irina Lyadova ◽  
Vladimir Yeremeev ◽  
Konstantin Majorov ◽  
Boris Nikonenko ◽  
Sergei Khaidukov ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Ex Vivo ◽  
Antimycobacterial Activity ◽  
Enzymatic Digestion ◽  
Interleukin 4 ◽  
T Cell Clones ◽  
Cell Clones ◽  
Ifn Γ

ABSTRACT I/St mice, previously characterized as susceptible toMycobacterium tuberculosis H37Rv, were given 103 or 105 CFU intravenously. At two time points postinoculation, the cell suspensions that resulted from enzymatic digestion of lungs were enumerated and further characterized phenotypically and functionally. Regarding the T-cell populations recovered at 2 and 5 weeks postinfection, two main results were obtained: (i) the population of CD44− CD45RB+cells disappeared within 2 weeks postinfection, while the number of CD44+ CD45RB−/low cells slowly increased between weeks 2 and 5; (ii) when cocultured with irradiated syngeneic splenocytes, these lung T cells proliferated in the presence of H37Rv sonicate. Using H37Rv sonicate and irradiated syngeneic splenocytes to reactivate lung T cells, we selected five CD3+CD4+ CD8− T-cell clones. In addition to the H37Rv sonicate, the five clones react to both a short-term culture filtrate and an affinity-purified 15- to 18-kDa mycobacterial molecule as assessed by the proliferative assay. However, there was a clear difference between T-cell clones with respect to cytokine (gamma interferon [IFN-γ] and interleukin-4 [IL-4] and IL-10) profiles: besides one Th1-like (IFN-γ+ IL-4−) clone and one Th0-like (IFN-γ+ IL-4+IL-10+) clone, three clones produced predominantly IL-10, with only marginal or no IL-4 and IFN-γ responses. Inhibition of mycobacterial growth by macrophages in the presence of T cells was studied in a coculture in vitro system. It was found that the capacity to enhance antimycobacterial activity of macrophages fully correlated with INF-γ production by individual T-cell clones following genetically restricted recognition of infected macrophages. The possible functional significance of cytokine diversity among T-cell clones is discussed.

scholarly journals Polarization of Allogeneic T-Cell Responses by Influenza Virus-Infected Dendritic Cells

2000 ◽  
Vol 74 (17) ◽  
pp. 7738-7744 ◽  
Author(s):  
Sangkon Oh ◽  
Maryna C. Eichelberger
Keyword(s):  
Immune Response ◽  
T Cells ◽  
Dendritic Cells ◽  
Influenza Virus ◽  
T Cell ◽  
Interleukin 2 ◽  
Dependent Manner ◽  
Ifn Γ ◽  
High Doses ◽  
Type Response

ABSTRACT The developing immune response in the lymph nodes of mice infected with influenza virus has both Th1- and Th2-type characteristics. Modulation of the interactions between antigen-presenting cells and T cells is one mechanism that may alter the quality of the immune response. We have previously shown that the ability of dendritic cells (DC) to stimulate the proliferation of alloreactive T cells is changed by influenza virus due to viral neuraminidase (NA) activity. Here we show that DC infected with influenza virus A/PR/8/34 (PR8) stimulate T cells to produce different types of cytokines in a dose-dependent manner. Optimal amounts of the Th1-type cytokines interleukin-2 (IL-2) and gamma interferon (IFN-γ) were produced from T cells stimulated by DC infected with low doses of PR8, while the Th2-type cytokines IL-4 and IL-10 were produced only in response to DC infected with high doses of PR8. IL-2 and IFN-γ levels corresponded with T-cell proliferation and were dependent on the activity of viral NA on the DC surface. In contrast, IL-4 secretion required the treatment of T cells with NA. Since viral particles were released only from DC that are infected with high doses of PR8, our results suggest that viral NA on newly formed virus particles desialylates T-cell surface molecules to facilitate a Th2-type response. These results suggest that the activity of NA may contribute to the mixed Th-type response observed during influenza virus infection.

scholarly journals Phosphoantigen-activated Vγ2Vδ2 T cells antagonize IL-2–induced CD4+CD25+Foxp3+ T regulatory cells in mycobacterial infection

Blood ◽  
2009 ◽  
Vol 113 (4) ◽  
pp. 837-845 ◽  
Author(s):  
Guangming Gong ◽  
Lingyun Shao ◽  
Yunqi Wang ◽  
Crystal Y. Chen ◽  
Dan Huang ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Treatment Regimen ◽  
T Regulatory Cells ◽  
Mycobacterial Infection ◽  
T Cell Subsets ◽  
Regulatory Cells ◽  
Ifn Γ ◽  
Vγ2vδ2 T Cells

Abstract Although Foxp3+ T regulatory cells (Tregs) are well documented for their ability to suppress various immune cells, T-cell subsets capable of counteracting Tregs have not been demonstrated. Here, we assessed phosphoantigen-activated Vγ2Vδ2 T cells for the ability to interplay with Tregs in the context of mycobacterial infection. A short-term IL-2 treatment regimen induced marked expansion of CD4+CD25+Foxp3+ T cells and subsequent suppression of mycobacterium-driven increases in numbers of Vγ2Vδ2 T cells. Surprisingly, activation of Vγ2Vδ2 T cells by adding phosphoantigen Picostim to the IL-2 treatment regimen down-regulated IL-2–induced expansion of CD4+CD25+Foxp3+ T cells. Consistently, in vitro activation of Vγ2Vδ2 T cells by phosphoantigen plus IL-2 down-regulated IL-2–induced expansion of CD4+CD25+Foxp3+ T cells. Interestingly, anti–IFN-γ–neutralizing antibody, not anti–TGF-β or anti–IL-4, reduced the ability of activated Vγ2Vδ2 T cells to down-regulate Tregs, suggesting that autocrine IFN-γ and its network contributed to Vγ2Vδ2 T cells' antagonizing effects. Furthermore, activation of Vγ2Vδ2 T cells by Picostim plus IL-2 treatment appeared to reverse Treg-driven suppression of immune responses of phosphoantigen-specific IFNγ+ or perforin+ Vγ2Vδ2 T cells and PPD-specific IFNγ+αβ T cells. Thus, phos-phoantigen activation of Vγ2Vδ2 T cells antagonizes IL-2–induced expansion of Tregs and subsequent suppression of Ag-specific antimicrobial T-cell responses in mycobacterial infection.

Tofacitinib modulates the VZV-specific CD4+ T cell immune response in vitro in lymphocytes of patients with rheumatoid arthritis

Rheumatology ◽  
2019 ◽  
Vol 58 (11) ◽  
pp. 2051-2060 ◽  
Author(s):  
Giovanni Almanzar ◽  
Felix Kienle ◽  
Marc Schmalzing ◽  
Anna Maas ◽  
Hans-Peter Tony ◽  
...  
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Cd4 T Cells ◽  
Granzyme B ◽  
Janus Kinase ◽  
Cell Immune Response ◽  
Dependent Manner ◽  
Th1 Response

AbstractObjectiveRA is a chronic inflammatory disease characterized by lymphocyte infiltration and release of inflammatory cytokines. Previous studies have shown that treatment with Janus kinase inhibitors, such as tofacitinib, increased the incidence rate of herpes zoster compared with conventional DMARDs. Therefore, this study aimed to investigate the effect of tofacitinib on the varicella-zoster-virus (VZV)-specific T cell immune response.MethodsThe effect of tofacitinib on the VZV-specific T cell immune response was determined by evaluating the IFNγ production, the proliferative capacity, the VZV-induced differentiation into effector and memory T cells, the expression of activation marker CD69 and helper T cell type 1 (Th1)-characteristic chemokine receptors, such as CXCR3 and CCR5, as well as cytotoxic activity (perforin and granzyme B expression) of CD4+ T cells of patients with RA compared with healthy donors upon stimulation with VZV antigen in vitro.ResultsTofacitinib significantly reduced the IFNγ production, proliferation, activation, and CXCR3 expression of VZV-specific CD4+ T cells in a dose-dependent manner in short- and long-term lymphocyte culture. No effect on the distribution of naive, effectors or memory, or on the expression of perforin or granzyme B by VZV-specific CD4+ T cells was observed.ConclusionThis study showed that tofacitinib significantly modulated the Th1 response to VZV. The poor VZV-specific cellular immune response in patients with RA may be considered in recommendations regarding appropriate vaccination strategies for enhancing the VZV-specific Th1 response.

scholarly journals Analysis of the defects responsible for the impaired regulation of Epstein-Barr virus-induced B cell proliferation by rheumatoid arthritis lymphocytes. I. Diminished gamma interferon production in response to autologous stimulation.

1983 ◽  
Vol 157 (1) ◽  
pp. 173-188 ◽  
Author(s):  
F Hasler ◽  
H G Bluestein ◽  
N J Zvaifler ◽  
L B Epstein
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
B Cell ◽  
Epstein Barr Virus ◽  
Gamma Interferon ◽  
Barr Virus ◽  
T Cell Regulation ◽  
Epstein Barr

T cells of patients with rheumatoid arthritis (RA) do not control the rate of B lymphoblast transformation induced by Epstein-Barr virus (EBV) as efficiently as T cells from healthy individuals; thus, lymphoblast cell lines are established more readily in RA lymphocytes in vitro after EBV infection. In the present experiments, we have asked whether this T cell regulation can be reproduced by lymphocytes. We found that normal T cells, activated in allogeneic or autologous mixed leukocyte reactions (MLR), produce lymphokines that inhibit in vitro EBV-induced B cell proliferation. Allogeneic MLR supernatants inhibited EBV-induced DNA synthesis 62 +/- 4% (mean +/- SE) at 10 d post-infection, whereas autologous MLR supernatants suppressed it 50 +/- 3%. RA T cell supernatants produced in an allogeneic MLR suppressed as well as normal T cell supernatants (64 +/- 5% inhibition). In contrast, supernatants from RA autologous MLR had little inhibitory activity. EBV-induced DNA synthesis at 10 d was reduced only 8 +/- 3%, compared with the 50 +/- 3% suppressive activity of normal autologous MLR supernatants. The magnitude of the proliferative responses in the autologous MLR regenerating the lymphokines was similar in the normal and RA populations. After depletion of adherent cells from the RA auto-MLR stimulators, supernatant inhibitory activities increased to normal levels (from 11 +/- 6 [SE] to 52 +/- 6% [SE]). The inhibitory factor involved in the regulation of in vitro EBV infection is a protein with a molecular weight of approximately 50,000. Its activity is eliminated by hearing at 56 degrees C and by exposure to acid at pH 2. The inhibitory activity is blocked by mixing the MLR supernatants with a polyvalent antisera or monoclonal antibodies specific for human gamma interferon. Gamma interferon produced by activating T cells in allo- or auto-MLR can reproduce T cell-mediated regulation of EBV-induced B cell proliferation, and the failure of RA auto-MLR to generate that lymphokine parallels the defective T cell regulation of EBV-induced B cell proliferation characteristic of RA lymphoid cells.

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