Deficiency of the autologous mixed lymphocyte reaction in patients with autoimmune thyroid disease

Regulatory T Cells in Autoimmune Diseases: Anti-Ergotypic T Cells

T regulatory cells play an important role in regulating T-cell responses to self-antigens and control autoimmunity and autoimmune disease. Anti-ergotypic T cells are a subset of such regulatory T cells that respond to activation markers, ergotopes, expressed on other activated T cells. Anti-ergotypic T cells do not respond to nonactivated T cells. Ergotopes include the a-chain of the IL-2 receptor (CD25). Anti-ergotypic T cells were found to downregulate experimental diseases such as experimental autoimmune encephalomyelitis (EAE) and adjuvant arthritis (AA). Anti-ergotypic T cells are present in humans and are activated after T-cell vaccination. Here we review anti-ergotypic T cells in animal models and in humans and contrast anti-ergotypic T cells with other regulatory T-cell subsets.

Reduced activation of suppressor T lymphocytes by specific antigens in autoimmune thyroid disease

In order to study the activation of suppressor T lymphocytes by thyroid-specific antigens in autoimmune thyroid disease (AITD), we have investigated the effects of the organ-specific antigens, thyroperoxidase (TPO), thyroglobulin (Tg), and thyroid microsomal antigen (TMc), as well as renal microsomes (RMc) as a control antigen, on the activation of suppressor T lymphocytes; this was accomplished by measuring major histocompatibility complex class II (HLA-DR) expression on their surfaces by flow cytometric analysis. Peripheral blood mononuclear cells (PBMC), obtained from 33 patients with Graves' disease (GD), 26 with Hashimoto's thyroiditis (HT), 5 with nontoxic nodular goiter (NTG), and 30 normal persons (N), were cultured for 7 days in the presence or absence of TPO, Tg, or RMc at final concentration of 10, 100, and 1000 ng/ml. Cultured cells were stained with fluorescent-conjugated monoclonal antibodies (anti-CD8, anti-CD11b, and anti-HLA-DR), and the activation of CD8+ and CD8+CD11b+ (pure suppressor) T cells by the antigens was analyzed on a flow cytometer. In the absence of antigen, i.e., the autologous mixed lymphocyte reaction (AMLR), CD8+ and CD8+CD11b+ T lymphocytes from patients with GD and HT showed significantly lower activation as compared to N. We measured the Stimulation Index (Sl) of activated T lymphocytes to compare antigen-specific activation between CD8+ and CD8+CD11b+ cells from normal persons and patients. With stimulation of 100 and/or 1000 ng/mL of TPO or Tg, Sl of activated CD8+ cells was significantly (p < 0.05 to 0.01) lower in GD and HT as compared with N.(ABSTRACT TRUNCATED AT 250 WORDS)

Sensitization of T lymphocytes to thyroglobulin and thyroperoxidase in autoimmune thyroid diseases

To investigate T-cell sensitization to thyroid autoantigens in autoimmune thyroid disease (AITD), purified soluble human thyroglobulin (Tg) and thyroid peroxidase (TPO) were used. Peripheral blood mononuclear cells (PBMC) as well as CD8-depleted, CD4-enriched PBMC ("selected" PBMC) from 9 patients with Graves' disease (GD), 13 Hashimoto's thyroiditis (HT) and 10 healthy subjects, were cultured for 6 days with or without varying concentrations (0.1, 1.0 and 5.0 micrograms/ml, respectively) of Tg or TPO and their responses were evaluated using the 3H-thymidine incorporation assay. Total PBMC as well as selected PBMC from GD and HT responded to both TPO and Tg, but normal PBMC did not. This induction was more marked in "selected" PBMC; on the other hand, CD8 depletion did not permit normal PBMC to respond to either antigen. However, reactivity of selected AITD PBMC to Tg differed from that of TPO. Two way analysis of variance showed that the proliferative response was significantly greater with Tg than with TPO, (again particularly notable with the "selected" PBMC) in both GD and HT. There was no difference between control and AITD preparations when an irrelevant (renal microsomal) antigen was employed. Taken together with our previous report that CD4 cells were induced by TPO even when cultured with CD8 cells, it is evident that suppressor CD8 cells do play a role in CD4 cells from proliferating against Tg and TPO; however their function alone or in combination with suppressor-inducer CD4 cells is partially disturbed, so that T cell sensitization to Tg and TPO can be identified in the AITD PBMC.

Studies of CD4+ (helper/inducer) T lymphocytes in autoimmune thyroid disease: demonstration of specific induction in response to thyroid peroxidase (TPO) in vitro and its relationship with thyroid status in vivo

We have studied by flow cytometric analysis the antigen specific activation of CD4+ (helper/inducer) T lymphocytes by purified human thyroid peroxidase (TPO). Peripheral blood mononuclear cells were obtained from 26 patients with Graves' disease (GD), 16 with Hashimoto's thyroiditis (HT), 7 with nontoxic nodular goiter (NG), and 14 normal subjects (N). Cells were cultured for 7 days in the presence or absence of TPO at final concentrations of 3, 30, and 300 ng/mL. When harvested, cells were reacted with an FITC-conjugated anti-CD4 and a PE-conjugated anti-HLA-DR murine monoclonal antibodies. The percentage of HLA-DR+ CD4+ cells (activated CD4+ cells) was determined by a flow cytometer. In the absence of TPO, CD4+ cells had been activated without any specific stimulant. This is known as the autologous mixed lymphocyte reaction (AMLR). In the AMLR, CD4+ cells from GD and HT were less activated compared to those from NG and N. Results of TPO-specific activation were expressed as an incremental increase of activated CD4+ cells (II) (percentage of activated CD4+ cells cultured with TPO minus percentage of activated CD4+ cells cultured without TPO). II of N, GD, HT, and NG were 0.37 +/- 0.21, 2.20 +/- 0.45,** 2.0 +/- 0.66,* and 0.35 +/- 0.27 (mean +/- SEM), respectively (**p less than 0.01; *p less than 0.05 vs N). When patients were further subdivided, the highest mean II was found in patients with hyperthyroid GD (p less than 0.01), followed by euthyroid HT (p less than 0.05) and euthyroid GD (p less than 0.05), however there was no significant difference between hypothyroid HT and N. In conclusion (1) AMLR reactivity of CD4+ cells from GD and HT was impaired, (2) however, CD4+ cells from both GD and HT were significantly more induced by TPO compared to N, and (3) this induction depends, in part, on the in vivo thyroid status.

Functional involvement of the LFA-1/ICAM-1 adhesion system in the autologous mixed lymphocyte reaction

The integrin surface molecule termed lymphocyte functional antigen-1 (LFA-1), and its physiological ligand intercellular adhesion molecule-1 (ICAM-1), have been proven to play a relevant role in several immune reactions where cell-to-cell contact is required: these reactions include allogeneic mixed lymphocyte reaction (MLR) and direct cytotoxicity. In the present study, we show that monoclonal antibodies (mAbs) directed to LFA-1 as well as to ICAM-1 molecules are able to inhibit T cell proliferation in autologous MLR (AMLR). Such an in vitro reaction is generally considered a functional model of Ia-mediated immunocompetent cell cooperation, and is impaired in several pathological conditions. It is noteworthy that the LFA-1 molecule is largely represented on the T cell surface, whereas ICAM-1 is poorly expressed on resting T cells: autologous stimulation slightly increases ICAM-1 expression. Pretreatment studies indicate that the inhibitory effect of anti-ICAM-1 mAb on T cell proliferation in AMLR is exerted on responder T cells.

Activated CD4-positive T-lymphocytes and impaired cell-mediated immunity in patients with carcinoma of the urinary bladder with schistosomiasis

Patients with schistosomiasis of the urinary bladder (SB) associated with carcinoma of the bladder (SCB) or carcinoma of the prostate (SCP) have a variety of immunologic abnormalities, including the presence of HLA-DR+ and interleukin-2 receptor-positive (IL-2R+) T-lymphocytes in circulating blood. This study demonstrated that, the HLA-DR+ and IL-2R+ antigens are selectively expressed on majority of the CD4+ T-lymphocytes of patients with SCB, whereas, these antigens are expressed almost equally on both CD4+ and CD8+ T-lymphocytes of patients with SB and SCP. Expressions of HLA-DR+ and IL-2R+ antigens in CD4+ T-lymphocytes, and a depressed response of this T-cell subset to phytohemagglutinin and Concanavalin A stimulations seems to be the characteristic feature of these patients with SCB. In addition, the autologous mixed lymphocyte reaction (AMLR) and allogenic mixed lymphocyte reaction (MLR) was depressed in patients with SCB. However, patients with SCP demonstrated a normal MLR, even though the AMLR was highly depressed. The immunoregulatory role of the HLA-DR+, IL-2R+, CD4+ helper/inducer T-lymphocytes, and the AMLR and MLR abnormalities we have identified in patients with SCB may be important and could play a role in the pathobiology of these diseases in humans.

Class II HLA-DR antigens on non-autoimmune human thyroid cells stimulate autologous T cells with high suppressor activity

Human autoimmune thyroid cells "spontaneously" express MHC-class II antigens. These antigens have been assumed to trigger thyroid-specific helper T cell clones, leading in turn to the expansion of thyroid autoantibody-secreting B cells. Thyroid cells derived from non-autoimmune subjects do not express MHC-class antigens, but these can be readily induced with gamma-interferon. We have addressed the issue of whether it is sufficient for normal thyroid cells to bear class II antigens in order to trigger autologous T cells. We found that non-autoimmune thyrocytes expressing DR antigens fail to stimulate autologous resting T cells. However, proliferative activity and interleukin-2 secretion were observed when fresh T cells were first triggered by autologous non-T cells and then incubated with thyrocytes. More CD8 than CD4 cells proliferated in the T:thyrocyte cultures, but CD4 cells were necessary for the proliferation and interleukin-2 secretion. Addition of antibodies to thyroglobulin or to DR antigens inhibited T cell proliferation and interleukin-2 secretion, thus pointing to T cell recognition of both thyroid-specific and DR antigens. Evaluation of the function of the thyroid stimulated T cells revealed very potent suppressor but negligible helper and cytotoxic activities. It would seem, therefore, that DR-restricted T cell activation by autologous antigen on non-autoimmune thyroid cells does occur, but since it results in enhanced suppression, its nature seems protective, thus leading to maintenance of immunological self-tolerance.

Functional study of T lymphocyte responsiveness in patients with dementia of the Alzheimer type

The autologous mixed lymphocyte reaction (AMLR) was used to study T lymphocytes in a group of patients with dementia of the Alzheimer type (DAT) in order to confirm the observation that their T cell proliferation in AMLR was greater than in age-matched controls, and to investigate other pathways of T cell activation, searching for correlations between immunologic and clinical findings in DAT. The mean proliferative response in AMLR was increased in patients with DAT. No differences between patients and age-matched controls were detected when other pathways of T cell activation were investigated. The degree of response in the AMLR varied among patients with DAT. This fits with the suggestion that the disorder may be a heterogeneous syndrome.

Production of and response to interleukin-2 in Graves' disease

Interleukin-2 is a lymphokine which is believed to play a central role in the regulation of the immune response. The production of and response to interleukin-2 were determined in hyperthyroid Graves' patients together with thyroid function and serum thyrotropin receptor antibody, a marker of autoimmune activity. Interleukin-2 production by mitogen-induced peripheral blood mononuclears was markedly low in 24 of 29 patients when compared to controls. Five patients in remission had normal values. In nine patients followed during antithyroid drug therapy, interleukin-2 production returned gradually to normal levels within 4-6 months. This rise and the concomitant decrease in serum thyrotropin receptor antibody correlated with the decline in the free thyroxin index. Antithyroid drugs and triiodothyronine had no effect on interleukin-2 production in vitro. Mitogen-activated mononuclears from hyperthyroid Graves' patients did not proliferate as well as the controls in response to interleukin-2. However, seven patients treated with antithyroid drugs and three in remission responded normally. Flow cytometry using anti-Tac antibody revealed that the interleukin-2 receptor density on mononuclears from five patients was low. This parameter was normal in treated patients and those in remission. We conclude that the production of and response to interleukin-2 by peripheral blood mononuclears from hyperthyroid Graves' patients are poor, the latter being due to impaired receptor expression. Both aberrations are restored to normal by antithyroid drug therapy or in remission. The relative roles of the autoimmune process and thyroid function in modulating the interleukin-2 pathway and the question of whether antithyroid drugs act directly or through thyroid inhibition remain to be clarified.