Human muscle acetylcholine receptor reactive T and B lymphocytes in the peripheral blood of patients with myasthenia growth

The prevalence of T and B cells reactive with the acetylcholine receptor (AChR) of human skeletal muscle was studied in 33 patients with myasthenia gravis (MG), 18 patients with other neurological diseases (OND) or autoimmune disorders (AD) and 27 age- and sex-matched healthy controls. T cell stimulation was estimated by enumerating cells secreting interferon (IFN)-γ and interleukin (IL)-2 in response to the AChR, whereas B cell reactivity was estimated by enumerating cells secreting IgG antibodies binding to the AChR. AChR-reactive T cells were increased in the peripheral blood of patients with MG as compared to patients with OND, AD and healthy individuals. Of the patients with MG, 29/33 (87.7%) had numbers of IFN-γ secreting cells higher than the mean ± 2 SD of the mean of controls as compared to 4/18 (22.2%) of patients with OND or AD and 2/27 (7.4%) of the controls. The mean value of the numbers of AChR-reactive T cells in the patients with MG was 19.6/10⁵ PBMC, corresponding to 1/5100 PBMC. Comparable results were obtained also for IL-2-secreting cells. Anti-AChR IgG antibody-secreting cells were detected in the blood of 30/33 (91%) of the patients with MG, 3/18 (16.7%) of the patients with OND or AD and 2/25 (8%) of the controls. The mean value of the antibody-secreting cells in MG was 11.7 cells/10⁶ PBMC corresponding to 1/70400 PBMC in the patients with MG, compared to a mean value of antibody-secreting cells in the patients with OND or AD of 0.33 and controls of 0.16 cells/10⁶ PBMC.