Human monoclonal immunoglobulins that bind the human acetylcholine receptor

Myeloma immunoglobulins, once thought to be without any immunological function, are now known to be reactive with many antigens, including self components. We have screened 149 monoclonal immunoglobulin samples and found 14 (9%) to react with the human acetylcholine receptor (AChR). Such anti-AChR antibodies are often associated with the autoimmune disease myasthenia gravis (MG). The anti-AChR binding of the myeloma components was restricted to the F(ab')2 fragment and the affinities were similar to anti-AChR antibodies isolated from MG patients. Despite the presence of anti-AChR antibodies none of the patients exhibited any symptoms of MG.