Aspects of lymphocyte function in myasthenia gravis

Enhanced proliferative response of myasthenic thymus cells in mixed lymphocyte reaction

To determine the functional diversity of thymic lymphoid cells in patients with myasthenia gravis (MG), we evaluated mixed lymphocyte reactions (MLR) using thymus cells in 7 MG patients and 8 controls. In the MLR, we used thymus cells as responder cells and mitomycin C-treated peripheral non-T cells as stimulator cells. In an autologous MLR test, a low proliferative response was observed in both the MG patients and controls. In an allogeneic MLR test, in which thymus cells were co-cultured with allogeneic non-T cells, the thymus cells from MG patients showed an increased proliferative response to stimulator cells, whether they were from MG patients or the controls. However, thymus cells from the controls showed a low proliferative response to any allogeneic stimulator cells. The enhanced allo-reactivity of thymus cells from MG patients thus suggests that there is an increase in the number of functionally mature T lineage cells in the MG thymus.

Myasthenia gravis associated with adrenocortical insufficiency. Report of two cases

Two cases of Addison's disease associated with myasthenia gravis are reported. This association has been described only rarely in the literature. In the first case, there were marked immunological abnormalities. It is most likely that the origin of the adrenocortical insufficiency in the second case is tuberculous. The pathogenetic mechanism of these associations is briefly discussed.

Lymphocyte subpopulations and surface membrane immunoglobulins in myasthenia gravis

Lymphocyte subpopulations were studied in 16 myasthenic patients by means of E and EA7s rosettes and surface membrane immunofluorescence. Myasthenic patients showed an increase in lymphocytes with surface IgM an IgD when compared to a control group. In female patients this increase was highly significant, and lymphocytes bearing membrane IgG and IgA were also augmented. No difference was found in male patients when compared with sex-matched controls. These results suggest an activation of the B cell compartment restricted to female patients, and support the hypothesis of different immunopathogenetic mechanisms in this disease.

Monoclonal antibody analysis of blood T-cell subsets in myasthenia gravis

Analysis of peripheral blood T -cell subsets and B-cells in patients with myasthenia gravis was performed using monoclonal antibodies and antibody against surface immunoglobulins (SIg) in an immunofluorescent technique. We found a modest but significant decrease in percentages of OKT3- and OKT8-positive cells (thought to represent total T-cells and T-suppressor/cytotoxic cells, respectively) in myasthenics as a group. The percentage of OKT3-positive cells was significantly decrease in patients with late-onset disease (greater than 35 years old), while the percentage of OKT8-positive cells was significantly reduced in those with early-onset myasthenia (greater than 35 years old). Both thymectomized and nonthymectomized patients exhibited a decreased percentage of OKT3-positive cells. No significant difference was found between the percentages of SIg-positive cells in myasthenics and controls. Our results suggest that only modest imbalances of circulating immunoregulatory lymphocytes occur in myasthenia gravis; however, it is conceivable that the small differences observed in this study may reflect pathogenetically important reductions in a functionally distinct lymphocyte subpopulation.

Immune disease and HLA associations with myasthenia gravis

In the late 1950's laboratory and clinical evidence suggested that myasthenia gravis was an autoimmune disorder. Since then a voluminous literature has developed documenting the many immunological abnormalities that occur in this condition. Recent findings point to a central disorder of immunoregulation. It is postulated that the disease occurs as a result of host genetic and environmental influences-the latter being, as yet unidentified and possibly a virus.

Lymphocyte subpopulations and IgG concentrations in cerebrospinal fluid and blood from patients with myasthenia gravis

Twelve patients with myasthenia gravis (MG) were examined for cerebrospinal fluid (CSF) T lymphocytes and for peripheral blood lymphocyte subpopulations (E-, EAET-, EA- and EAC-rosette-forming cells). The patients had a significantly increased percentage of CSF T cells (88.2 +/- 8.7%) when compared with controls (78.0 +/- 9.1%). Absolute concentrations of CSF T cells were not significantly increased. In peripheral blood no significant change in lymphocyte subpopulations was observed, but there was a slight leucocytosis in the patient group. The patients had increased CSF IgG concentrations, CSF IgG to protein ratio, and CSF to serum IgG ratio, indicating an intrathecal production of IgG. No oligoclonal bands could be demonstrated in the agarose gel electrophoresis. The two patients with thymoma had anti-muscle antibodies in CSF and serum, with ratios of 1:256 and 1:1024, respectively. Serum IgG levels were increased, but not significantly, in the patient group. These results suggest an involvement also of the central nervous system in some patients with MG.

Myasthenia gravis with a monoclonal gammopathy--report of a case

An elderly man with relapsing myasthenia gravis was found to have hypergammaglobulinaemia, a monoclonal peak of gamma mobility and paraproteinaemia IgG, type K. Bence-Jones proteinuria, type K was present. This is the fourth report of myasthenia gravis associated with a monoclonal gammopathy. Myasthenia gravis is considered to be an autoimmune disease. Recent findings implicate a dysfunction of cellular immunity in the pathogenesis of both immunoproliferative and autoimmune disease. We suggest that the association of myasthenia gravis and monoclonal gammopathy in our patient might have stemmed from a disorder of T lymphocyte function.

Lymphocyte subpopulations in thymus and blood from patients with myasthenia gravis

Cell suspensions were prepared from hyperplastic thymic tissue and lymphoepithelioma from patients with myasthenia gravis and from presumed normal thymic tissue obtained at cardiac surgery. The mononuclear cells were examined for surface markers. The mean percentages of both T lymphocytes and Fc receptor-carrying lymphocytes were similar in the three groups, whereas there was an increase in C receptor-carrying lymphocytes in the samples from myasthenic patients. Sections from the thymus gland were examined for T and B markers. In the hyperplastic thymus and in lymphoepithelioma, the T lymphocytes were distributed diffusely throughout the cortex and the medulla; in the normal thymus they were predominant in the cortex. The mean percentage of T and B lymphocytes in peripheral blood from patients with myasthenia gravis was normal. Thymectomy involved a transitory decrease in T lymphocytes with a corresponding increase in B lymphocytes.

Assessment of cellular and humoral immunity of myasthenics

A close association of autoimmune diseases or autoimmune phenomena in myasthenia gravis is well known. A comprehensive immunological study of 22 patients with myasthenia gravis showed that changes in the immune system mainly involve the thymus-derived lymphocytes (T cells). Anti-thymus antibody was present in 90% of the patients, and it paralleled the frequency of thymic abnormality in myasthenia gravis. It is postulated that in myasthenia gravis the altered T cell functions caused by anti-thymus antibody result in the formation of an array of autoantibodies including the factor which blocks the neuromuscular transmission.