Analysis of immunoglobulin secretion by lymph organs with myasthenia gravis

OBJECTIVES: To investigate in vitro anti-acetylcholine receptor (AChR) antibody secretion by lymph organs with myasthenia gravis (MG) with special attention to clinical status and stages. MATERIALS AND METHODS: Twenty MG patients before therapy were included in this study. Four patients were negative for serum anti-AChR antibodies (AChRAb). All patients received extended thymectomy. Thymic cells, bone marrow (BM) cells and peripheral blood mononuclear cells (PBMC) were cultured for 1 week. AChRAb secretion and IgG secretion in the culture medium were determined by immunoprecipitation assays and ELISA respectively. RESULTS: PBMC secreted AChRAb and IgG most efficiently, followed by BM cells, and then thymic cells. Even in patients whose diseases were of short duration (less than 2 months), the tendency was not changed. AChRAb secretion by BM cells and PBMC significantly correlated with serum AChRAb levels. Thymectomy did not change AChRAb or IgG secretion by PBMC within 3 months. AChRAb secretion by PBMC paralleled the clinical status. Some seronegative patients turned positive by culturing PBMC. CONCLUSION: PBMC is the most efficient site at producing AChRAb, even in patients of short duration (equal to, or less than, 2 months). Monitoring AChRAb secretion by PBMC is useful to estimate the autoimmune activity of MG.