Comparative Studies on the Expression of CD5 B-Lymphocytes in Exprimental Autoimmune Masthenia Gravis (EAMG) and in Human Myasthenia Gravis

ABSTRACT

BACKGROUND: A human B-cell subpopulation which is identifiable by the expression of cell surface antigen Leu-1 (CD5) is known to be responsive for the antoantibody secretion. The exprimental autoimmune myasthenia gravis(EAMG) could be induced in animals by injecting AChR from electric eel and had the same clinical and pathophysiological characteristics with human myasthenia gravis(MG). The authors performed the study to compare the frequncy of CD5 positive B-lymphocytes in EAMGs with those in human MGs and to understand whether the EAMG showed the similar immunological feature as in human MG. METHOD: For EAMG the 50ug AChR from Torpedo Marmorata with Freund's adjuvant were injected to Lewis rats of 150-200mg three times. The CD5 positive B-lymphocytes from peripheral blood were double stained by the monoclonal PE conjugated anti-CD5 and FITC conjugated anti-rat CD45 antibodies in the EAMGs and by the PE conjugated ani-Leu-11(CD5) and FITC conjugated anti-human Leu-12(CD19) antibodies in human MGs. The expression of positive CD5 positive B-lymphocytes were calculated by the fluorescent activated cell sorter(FACS). RESULTS: The mean CD5 positive B-lymphocytes expression in four EAMGs was 15.05% with ranging from 10.2% to 20,0%, which was increased compared with those in control rats. The mean frequency of CD5 positive B-lymphocytes were 25.2+/-15.05% in human MG(N=25) and 16.0+/-13.5% in normal controls (N=20) respectively, which did not show any significant difference (P=0.08). However the expression of CD5 positive B-lymphocytes in human MGs was significantly correlated with the titer of anti-AChR antibody (P=0.04). CONCLUSION: The increased expression of CD5 positive B-lymphocytes might be associated with the EAMG pathomechansms, but their expression only showed possible correlation with the anti-AchR antibody titer with minimal role in pathogenetic process of human MG. Therefore it would be suggested that immunological process of EAMG (acute form of MG) be a little different from that of human MG, chronic form.