Paraproteins in primary biliary cirrhosis.

Paraproteins have rarely been described in primary biliary cirrhosis. Eighteen patients were identified as having both antimitochondrial antibodies, and a significant paraprotein by screening 950 patients with either a previously known paraprotein or documented antimitochondrial antibodies. The clinical spectrum included 11 patients with proven or probable primary biliary cirrhosis and five with a plasma dyscrasia, of whom two also had primary biliary cirrhosis Antimitochondrial antibody activity appeared polyclonal and unrelated to the paraprotein class. Whilst in patients with primary biliary cirrhosis antimitochondrial antibody activity was predominantly of IgG3 subclass with normal levels, there was no subclass restriction shown in the remainder and IgG3 levels were lowered.