The influences of thymectomy on the fas expression and T Cell subsets in peripheral blood lymphocyte from patients with myasthenia gravis

Abstract

Objective To investigate the influences of thymectomy on the Fas expression and T cell subsets in peripheral blood lymphocyte (PBL) from patients with myasthenia gravis ( MG), so as to make sure whether Fas-mediated apoptosis is involved in the mechanism of thymectomy in MG therapy. Methods We analyzed CD4 、CD8 and Fas expressions in PBL from 17 patients with MG and 13 healthy controls using flow cytometric analysis. Results The percentage of CD4-CD8+ cells in PB of MG patients without thymectomy was significant higher, while the percentage of CD4-CD8-8-cells was significant lower, compared with controls ( P ＜0. 05 ). The percentage of CD4-CD8 + cells in PBL of MG patients with thymectomy was significant lower than the ones without thymectomy( P ＜ 0. 05 ). The percentages of Fas + and CD8 + Fas + cells in PBL of MG patients without thymectomy, as well as the percentage of Fas + cells in PBL of MG patients with thymectomy, were significant higher than that of controls ( P ＜ 0. 05 ). The percentages of Fas + , CD4 + Fas + and CD8 + Fas + cells in PBL of MG patients with thymectomy were lower than the ones without thymectomy, but the differences were not significant ( P ＞ 0. 05 ). Conclusion T cell subsets in PBL from patients with MG is abnormal, compared with healthy control. After thymectomy, this abnormality could be revised. Fas expression on PBL of patients with MG is increased, which most likely reflects lymphocyte activation in vivo, as well as increased CD8 + T cell-mediated cytotoxic effect. Fas expression on PBL is decreased after thymectomy, which may be involved in the mechanism of thymectomy in MG therapy. Key words: Myasthenia gravis; Fas antigen; T cell subsets; Thymectomy