Autoimmune human T lymphocytes specific for acetylcholine receptor

Epstein-Barr virus-transformed B cells can present acetylcholine receptor to autologous autoreactive T cells

Epstein-Barr virus- (EBV-)transformed B cells were obtained from a patient with myasthenia gravis, who was also the donor of a T cell line specific for acetylcholine receptor (AChR). After three months of culture, the EBV-transformed B cells could effectively present native membrane-bound AChR to autologous AChR-specific T cells.

Fc gamma receptors and HLA-DR antigens on thymus cells in myasthenia gravis

Receptors for the Fc part of IgG (Fc gamma R) and HLA-DR antigens were detected in thymus tissue from patients with myasthenia gravis (MG) using monoclonal antibodies (B1D6 and OKIa1) in indirect immunofluorescence. The amount of Fc gamma R and HLA-DR antigens was increased on epithelial reticular cells and on interdigitating reticular cells in hyperplastic thymus as compared to normal thymus. In thymomas from MG patients the neoplastic epithelial cells expressed Fc gamma R, whereas only a few cells had HLA-DR antigens. Neither thymocytes nor B lymphocytes in the hyperplastic thymuses and in the thymomas were stained by B1D6.

Strategies for the modulation of neuroimmunological disease at the level of autoreactive T-lymphocytes

Cell lines of autoimmune T-lymphocytes have been established in several neuroimmunological model diseases and also in a human neurological autoimmune disease, myasthenia gravis. These cell lines generally have the T helper/inducer phenotype and recognize autoantigen in the context of class II histocompatibility antigens. Autoreactive helper T cell lines may become useful tools for the evaluation of new immunotherapeutic strategies. (1) Treatment with anti-Ia monoclonal antibodies presumably interferes with the interaction between Ia on the surface of antigen-presenting cells and the autoreactive T cell receptor; (2) Therapy with unmodified or modified autoantigen may be used to tolerize or delete the autoimmune T cells; (3) Monoclonal antibodies against the 'T cell domains' of autoantigen may prevent its recognition by the autoreactive T cells; (4) Treatment with monoclonal antibodies against T cell clonotypic or differentiation antigens may effectively delete or inactivate the autoreactive T cells. Furthermore, autoreactive helper T cells may be used to induce and establish anti-idiotypic suppressor T cell lines, or the autoimmune helper T cells may themselves display suppressive effects in an allogeneic system.

The cellular immunology of myasthenia gravis

The possible role of the thymus in autosensitization to the acetylcholine receptor (AChR) in myasthenia gravis is briefly discussed, and work on autoantibody synthesis in vitro is reviewed. Whereas blood lymphocytes sometimes make anti-AChR in response to mitogens, spontaneous production is more regularly observed in cells from lymph nodes, bone marrow and, above all, thymus, where it is selectively activated. Cell separation studies imply a dominant contribution by the germinal centre cells and plasma cells there, many of which are autonomous (i.e. no longer require T cell help). The need for germinal centre-directed immunosuppressive regimes is discussed.

Human T-cell clones from autoimmune thyroid glands: specific recognition of autologous thyroid cells

The thyroid glands of patients with autoimmune diseases such as Graves' disease and certain forms of goiter contain infiltrating activated T lymphocytes and, unlike cells of normal glands, the epithelial follicular cells strongly express histocompatibility antigens of the HLA-DR type. In a study of such autoimmune disorders, the infiltrating T cells from the thyroid glands of two patients with Graves' disease were cloned in mitogen-free interleukin-2 (T-cell growth factor). The clones were expanded and their specificity was tested. Three types of clones were found. One group, of T4 phenotype, specifically recognized autologous thyroid cells. Another, also of T4 phenotype, recognized autologous thyroid or blood cells and thus responded positively in the autologous mixed lymphocyte reaction. Other clones derived from cells that were activated in vivo were of no known specificity. These clones provide a model of a human autoimmune disease and their analysis should clarify mechanisms of pathogenesis and provide clues to abrogating these undesirable immune responses.

Myasthenia gravis: reactivation of clinical disease and of autoimmune factors after discontinuation of long-term azathioprine

In 15 patients with myasthenia gravis who were in stable clinical remission while receiving azathioprine, we monitored disease severity and serial autoantibody titers before and after discontinuation of azathioprine. Cellular immunoreactivity against tuberculin (PPD) and against Torpedo acetylcholine receptor (AChR) was measured serially in 11 patients. Eight of 15 patients (53%) had a clinical relapse after 3 to 11 months, necessitating the reinstitution of immunosuppressive treatment in 6 patients. Seven patients have remained clinically stable during an observation period of 20 to 40 months. Anti-AChR autoantibody titers correlated closely with the clinical course in the majority of patients, and rose markedly in 7 of the 8 patients who relapsed. Cellular stimulation indices correlated less closely with the clinical severity. Only in 3 patients did the clinical score, antibody titer, and cellular stimulation index rise concurrently. In 4 patients who had high cellular stimulation indices after the discontinuation of azathioprine, it was possible to isolate AChR-reactive inducer/helper T lymphocytes.