Up-regulated Expression of Fas Antigen in Peripheral T cell Subsets in Patients with Myasthenia Gravis

Purpose: Recent reports have linked various autoimmune diseases to defective Fas-mediated apoptosis or Fas expression. Here we aimed to determine whether Fas-mediated apoptosis is involved in the pathogenesis of myasthenia gravis (MG). Methods: The expression of Fas antigen in peripheral T cell subsets from 17 Chinese patients with MG and 13 healthy individuals was determined by flow cytometry, and its associations with clinical classification, thymus pathology, the concomitance with hyperthyroidism (HT) and corticosteroid treatment were investigated. Results: Compared with normal controls, a significantly up-regulated expression of Fas antigen was observed in the peripheral CD4+, CD4+CD8- and CD4-CD8- T cell subsets from patients with MG. Fas expression in CD4-CD8+ T cells of MG patients with normal thymus was significantly higher than that of patients with thymoma. Fas expressions in CD4+CD8+ T cells in MG patients with HT was significantly higher than controls and the ones without HT. Enhanced Fas expressions was found in CD4-CD8+ and CD4-CD8- T cells of MG patients with corticosteroid treatment, but no significant difference of Fas expression in peripheral T cells between patients with ocular MG (OMG) and general MG (GMG) was observed. Conclusion: Fas antigen may play a role in the pathogenesis of MG. It may be involved in the mechanisms of corticosteroid treatment, and with the occurrence of HT. OMG may represent a systemic disease, similar to that of GMG.