A follow-up study of 68 patients with anti-mitochondrial antibodies (AMA).

During the period 1976-83, anti-mitochondrial antibodies (AMA) were detected in 68 patients out of about 48 000 sera (0.14%) analyzed for a repertoire of autoantibodies at the Department of Immunology, University Hospital of Tromsø. Fifty-five of these patients were women, and only 10 had unequivocal primary biliary cirrhosis (PBC). At follow-up in 1984, 48 out of these 68 patients were accessible for complementary testing. The AMA test became negative in 17 of these 48 patients during the observation period. Eleven of these 17 had originally a titer of 50. Seven of the 31 patients with persistent AMA were without detectable liver pathology. One patient had antibodies against smooth muscle, one against cell nucleus, whereas 35 had an increased serum IgM level. In conclusion, most patients with AMA do not have obvious PBC, a low AMA titer is likely to be transient, and there is a strong association between AMA and an increased serum IgM level.