The Cd5⁺ B Cells and Myasthenia Gravis

Abstract

A high frequency of CD5⁺ B lymphocytes in the peripheral blood of patients with myasthenia gravis (MG) has been reported recently. These results seem to indicate an attractive linkage between CD5⁺ B lymphocytes and autoantibodies against Acetylcholine receptor in MG. We examined the frequency of CD5⁺ B cells in 20 patients with MG and 21 normal healthy controls by two-color flow cytometry. However, there were no significant differences in the percentages of CD5⁺ B lymphocytes between the two groups. We also examined the frequency of CD5⁺ B lymphocytes in the resected thymus of patients. The frequency of CD5⁺ B lymphocytes in the thymus was low and similar pattern to that in the peripheral blood. We checked the antibody (Ab) production against the human acetylcholine receptor in either CD5⁺ B or CD5⁺ B lymphoctes using B lymphoblastoid cell line generated from the lymphocytes of 11 patients with anti-AChR Abs in the sera. Abs against the AChR in the human were mostly produced by CD5⁺ B, not CD5⁺ B lymphocytes. The anti-AChR Abs (IgG) production of CD5⁺ B cells and CD5⁺ B cells (mean ± SD) were 6.8 ± 2.4 fmol/ml and 18.5 ± 17.6 fmol/ml, respectively. These results sugget that in MG, the frequencies of the CD5⁺ B lymphocytes in PBL may be genetic background and that there may be no strong linages between AChR Ab production and CD5⁺ B lymphocytes.

Key Words:

• thymocytes
• two-color analysis
• flow cytometry
• thymectomy