Seasonal variation in suppressor T cell subsets and non-specific suppressor cell function in hay fever sufferers

The helper/suppressor T cell ratio, as defined by monoclonal antibodies, was significantly higher in hay fever sufferers compared with controls (P less than 0.05), but only during or shortly after the pollen season. This was due to a reduction in the suppressor subset, which returned to control values in the winter. There was no significant difference in the non-specific concanavalin A-induced suppressor cell function compared with controls. The mean summer value was significantly lower than the winter value (P less than 0.05), but we cannot be sure that this was not the result of changes in laboratory conditions. No relationship was found between T cell subsets or suppressor cell function and total or specific IgE levels, or between T cell subsets and suppressor cell function. Our findings suggest that in hay fever, reduction in suppressor cell numbers and function is a secondary phenomenon.     

IL-2 normalizes defective suppressor T cell function of patients with systemic lupus erythematosus in vitro

During autologous mixed lymphocyte reaction (AMLR) both helper and suppressor T cells capable of regulating B cell responses are generated. The proliferative response of T cells as well as the generation of T suppressor cells in the AMLR of patients with active systemic lupus erythematosus (SLE) is diminished. In contrast, the T helper cells generated in the AMLR show a hyperactivity. The diminished HLA-class II antigen expression observed on non-T cells of SLE origin was restored by treatment of the cells with gamma-interferon (gamma-IFN). When tested by immunoglobulin secretion, gamma-IFN enhanced T helper cell activity but failed to affect T cell proliferation and T suppressor cell generation in the AMLR derived from patients with SLE. Human recombinant interleukin 2 restores both the proliferative response of T cells and the induction of T suppressor cells in AMLR.     

T suppressor cell function and number in children with liver disease.

Con A stimulated suppressor cell function and the proportion of suppressor T cells were reduced in children with untreated chronic active hepatitis (CAH) but were normal in corticosteroid treated CAH patients, patients with severe acute hepatitis and inactive chronic liver disease. Adults with CAH also have defective suppressor function but a normal proportion of T suppressor cells. This difference may account for the observation that relapse after treatment withdrawal is less frequent in children than in adults.     

Cyclosporin A abrogates proliferation of T cells and generation of suppressor and cytotoxic T-cell function induced by Epstein-Barr virus

Cyclosporin A (CYA) promotes the outgrowth in vitro of Epstein-Barr-virus(EBV)-infected cells of immune donors. In the present study, the effects of CYA on the T-cell responses developed to an in-vitro EBV infection were studied. Cyclosporin A, by acting on the responder cells and not on stimulator cells, strongly inhibited the proliferation of T cells normally induced by EBV-infected autologous cells. Moreover, T cells from cultures not exposed to CYA exerted suppression on both alloantigen-induced DNA synthesis and PWM-stimulated immunoglobulin producton of autologous peripheral blood mononuclear cells. In contrast, T cells from cultures treated with CYA exhibited significantly less or no suppressor activity as determined in both indicator system. Finally, CYA abrogated the generation of cytotoxic T cells against EBV-infected autologous cells, whereas non-CYA -treated T cells killed the virus-transformed target cells. Both suppressor and cytotoxic T-cell functions are known to play an essential role in the control of EBV infection by limiting the continuous growth of the virus-infected cells. These results, therefore, stongly suggest that cyclosporin A promotes the outgrowth of EBV-infected cells by abrogating the T-cell responses to the Epstein-Barr virus.     

T cell antigen receptor engagement abrogates CD4-mediated T cell deletion in vivo

We have previously shown that the engagement of CD4 by specificantibody in the mouse initiates a T cell apoptosis responsewith the following features: spleen and lymph node CD4⁺ T cellsmigrate into the bloodstream within minutes of anti-CD4 administrationwhere they exhibit the phenotype of null cells. If they arecapable of expressing functional Fas protein on their surfacethey degrade their DNA and disintegrate rapidly. We show herethat the engagement of the T cell antigen receptor blocks theCD4-medlated deletion process in mouse. Anti-CD4-reactive Tcells avoid the exodus into the bloodstream when their TCR Isengaged by anti-CD3 or by a superantigen, do not modulate surfacereceptors and are not deleted. In contrast to the apoptoslsinducingCD4-specific antibody which causes migration of lymphocytesfrom lymphoid organs into the blood stream, the T cell-activatingCD3-specific antibody causes lymphoid cell redistribution inthe opposite direction, from the bloodstream to lymphoid organs.The TCR-mediated protection of T cells against CD4-mediateddeletion lasts for several hours but ceases before the T cellsbecome blasts.     

Mitogen-induced suppressor T cell activity in the in vitro cellular immune response.

A 24 h preincubation of human peripheral lymphocytes (PBL) in the presence of phytohemagglutinin (PHA) or concanavalin A (Con. A) renders them suppressive for the response of untreated cells to PHA, Con. A, candidin and allogeneic cells. However, cells stimulated with lipopolysaccharide (LPS) show no suppression.     

Human suppressor T cells induced in vitro with an autologous renal allograft-derived T cell line. I. Suppressor cell induction, function, and specificity

The functional characteristics of T suppressor (Ts) cells generated from the peripheral blood lymphocytes (PBL) of a kidney transplant recipient who had excellent graft function for 1 year were examined. Ts cells were induced by co-culture of PBL with an autologous alloreactive cytotoxic T lymphocyte (CTL) line (EE-1) previously grown from a routine renal allograft biopsy of this patient performed 10 days posttransplant. The EE-1 line included CD3+ T cells of CD8+ and CD4+ phenotypes with cytotoxic specificity for disparate class 1 (HLA-B8) and class II (HLA-DR1 and 3) antigens of the kidney donor (JC). The EE-1 induced Ts cell lines (designated TsEE) were found to significantly suppress (50%-95%) autologous fresh responder EE-PBL stimulation by donor EBV-transformed cells (JC-EBV) in mixed lymphocyte reaction (MLR) assay. TsEE cells were CD3+ (98%) and predominantly CD8+ (68-80%), showed no cytotoxic activity, and were suppressive only at the early phase of MLR stimulation. In three-party cell test MLR assays, TsEE-mediated suppression appeared restricted to responder cells sharing HLA-B7 with the suppressor line, and was not abrogated by the addition of exogenous interleukin-2 (IL-2). TsEE cells also showed restricted suppression of CTL generation but not mature CTL activity. The restricted suppressor activity of TsEE lines was dependent upon their induction and restimulation with the autologous EE-1 line.     

In vitro X-ray irradiation of human peripheral blood T lymphocytes enhances suppressor function

We studied the effect of in vitro X-ray irradiation on human peripheral blood T lymphocytes, with regard to their suppressor activity related to the concanavalin A (Con A)-induced suppressor system. To generate suppressor T lymphocytes, purified human T lymphocytes were incubated for 3 days in the first culture, with or without Con A. These lymphocytes were irradiated with various doses of X-ray before, mid or after the culture. After doing a second culture for 6 days, we measured the suppressive influence of these cells on T lymphocyte proliferation rates stimulated with allogeneic mononuclear cells, and B lymphocyte proliferation rates stimulated with pokeweed mitogen. Irradiation (1,000 rad) of cultures to which Con A had not been added induced much the same level of suppressor activity as seen in the cultures with Con A. The suppressor activity gradually increased with lapse of time from the irradiation to the suppressor cell assay. Suppressor T lymphocytes were resistant to X-ray irradiation and independent of DNA synthesis. On the other hand, irradiation-induced enhancement was minimal in cultures incubated with Con A, regardless of the irradiation time. As irradiation of human peripheral blood T lymphocytes was found to induce a suppressor function in vitro, clinical and experimental applications of irradiation in cases of a suppressed T lymphocyte function may be feasible.     

Dissection of suppressor cell generation in vitro

Suppressor cells (SC) that nonspecifically inhibited lymphoproliferative (LP) responses were found after culturing peripheral blood mononuclear cells: with suppressor T-cell clones, in mixed lymphocyte cultures (MLC), and with recombinant interleukin 2 (IL-2), but were not found after culture in medium alone. A monoclonal anti-IL-2 receptor (R) antibody (MoAb), TU69, which blocked LP responses of IL 2-dependent T-cell lines, also blocked SC induction by T-cell clones, but completely failed to inhibit SC generation in MLC or with IL-2. This suggests that the IL-2R epitope defined by TU69 was not involved in SC induction in the latter systems. MoAb against HLA-DQ (TU22), -DR (TU34, SG157), -DP (B7/21), or DR and DP (TU43, 58), all of which were able to block stimulation of appropriately specific clones, did not block SC induction in any of the three systems studied. In contrast, the broadly reactive moAb TU39, which binds at least DR and DP but also has additional reactivity for determinants tentatively designated "DY," blocked SC induction by T-cell clones and in MLC. Finally, an anti-HLA class I MoAb, W6/32.HL, greatly decreased SC generation in MLC, but not with rIL-2 or T-cell clones. Thus, the induction of nonspecific SC was dissected into three pathways involving: class I and TU39-defined but not DR, DQ, or DP determinants (in MLC) which was independent of the IL-2R epitope bound by TU69; only TU39-defined determinants (with T-cell clones), which were IL 2R dependent; and, neither class I, class II nor TU39-defined determinants (induction by rIL-2), which was also TU69+ IL-2R independent.     

自身免疫性甲状腺疾病外周血淋巴细胞体外分泌IgG及抑制功能的研究

本实验在体外测定了自身免疫性甲状腺疾病(autoimmune thyroid disease,AITD)患者外周血淋巴细胞培养的上清IgG含量,并根据Concanaralin(ConA)可诱导抑制性T细胞(suppressor T cell,Ts)的原理,检测了ConA诱导Ts对淋巴细胞分泌IgG的抑制率(suppressiverate,SR)。结果表明AITD患者淋巴细胞分泌IgG与正常人无明显差别(P>0.05),而其SR较正常对照显著低下(P<0.05),且SR与Graves病患者血T_3值呈负相关。实验进一步证明甲状腺素在体外并不影响ConA诱导Ts的抑制作用。本研究结果支持本病具有Ts功能的缺陷,且提示这种异常并不是继发于本病,而是本病原发性的免疫表现。     

In vitro studies of suppressor cell function in human peripheral blood mononuclear cells.

Peripheral blood mononuclear cells (PBMC) from normal donors, pre-cultured at 37 degrees C for 24 hr before the addition of mitogen, demonstrated an enhanced proliferative response. This may be due to the loss of a subpopulation of suppressor cells during the incubation period. Still further enhancement was observed when pre-culturing was prolonged for 48 hr, while cells pre-incubated at 4 degrees C showed no increased responsiveness. Concanavalin A (Con A) pre-activated PBMC supressed the mitogen response of responder cells. More marked suppression was observed when the concentration of Con A used to induce the suppressor cells was increased. It was not possible to activate suppressor function in cells which had been kept in vitro for longer than 48 hr. These findings support the concept of the existence and function of suppressor cells, and that the suppressive influence is short-lived in vitro culture.     

Rapid assessment of in vitro expanded human regulatory T cell function

Human regulatory T cells (Treg) are able to actively suppress autoreactive immune responses. Phenotypically, they are broadly characterized as CD4+, CD25+, CD127(lo/?) and FoxP3+. CD45RA can be used to further differentiate the population into na?ve (CD45RA(+)) and induced (CD45RA?) Treg. The functional potential of Treg is routinely determined by assessing their ability to suppress T cell function in 3-5day proliferation assays. Since Treg are being explored for therapeutic use, a short-term functional assay could serve as a valuable tool for evaluating the potency of Treg. Therefore, an assay designed to measure Treg suppression of activation marker expression by responder T cells in 7 to 20h has been examined in this report. Using flow cytometry, expression of CD69 and CD154 on T cells, in response to stimulation with CD3/CD28 beads, was used as a measure of activation in the assay. Treg from healthy volunteers were sorted as CD4+CD25+CD127(lo/?)CD45RA+ cells with a BD FACSAria? II. The highly purified Treg were then expanded in vitro and their function was assessed in short term activation marker suppression assays using autologous PBMC as responder cells. The data suggest that this short term suppression assay could be a reliable surrogate for assessing Treg functional potential.     

Impaired in vitro regulatory T cell function associated with Wiskott-Aldrich syndrome

Wiskott-Aldrich syndrome (WAS) is a primary immunodeficiency characterized by the contradictory coexistence of impaired T-cell function and exaggerated T-cell-mediated pathology, including autoimmunity and eczema. WAS protein (WASp)-deficient mice are also immunodeficient and can develop autoimmune disease. Since defects in regulatory T-cells (Treg) are associated with autoimmunity, we examined the presence and function of these cells in WAS patients and WASp-deficient mice. We found that CD4(+)CD25(+)FOXP3(+) Treg cells can develop in the absence of WASp expression. However, Treg cells both from WASp-deficient mice and from four out of five WAS patients studied showed impaired in vitro suppressor function. In WASp-deficient mice, this defect could be partially rescued by pre-activation with IL-2, suggesting that inadequate cell activation may play a role in WASp-deficient Treg dysfunction. These findings may provide insights into the complex pathophysiology and paradoxical phenotypes of WAS and suggest new therapeutic modalities for autoimmunity in these patients.     

Loss of suppressor T cell function and circulating immune complexes in chronic active liver diseases

Suppressor T cell function is decreased in patients with chronic active liver diseases (CALD). To account for the alterations, we examined the effect of sera of patients with various liver diseases on concanavalin A (Con A) induced suppressor T cell activity of normal individuals. The suppressor T cell activity was inhibited by heat-inactivated serum pretreatment in 13 of 27 cases of patients with CALD and in five of 11 cases of patients with acute viral hepatitis, whereas only two sera of 18 patients with other liver diseases affected suppressor cell activity. Using a 125I-C1q-binding test, a significant correlation (P less than 0.01) was detected between the degree of inhibition in the development of suppressor T cells and the level of circulating immune complexes in the sera of CALD patients. The blocking effect of patients' sera disappeared when the immune complexes were removed with polyethylene glycol. These data suggest that circulating immune complexes modulate cellular immunity in patients with CALD by influencing the suppressor T cell function.     

Evidence for distinct epitopes on human IgG with T cell proliferative and suppressor function

The Fc or pFc' fragments of the human IgG were demonstrated to exert different effects on murine T lymphocyte subsets. Thus, murine lymph node (LN) T cells were specifically induced to proliferate in vitro to pFc' after priming in vivo. This proliferation could be inhibited, either by depleting the responding LN population of macrophages, or by monoclonal antibodies specific for responder haplotype Ia antigenic determinants. Priming in vivo and subsequent restimulation in vitro with Fc resulted in the activation of a suppressor T cell subpopulation which, in an antigen-specific manner, could highly suppress proliferative responses. T cell subset isolation showed that the pFc'-specific proliferation was performed by Lyt-1+2- cells whereas the suppressor Fc-specific cells were of Lyt-1-2+ phenotype. Our data demonstrate that distinct epitopes on the human gamma chain induce either Ir gene-restricted T cell proliferation (pFc' fragment) or T cell suppressor function (Fc fragment).