Studies in primary biliary cirrhosis.

Monomeric (75) IgM was measured in 25 patients with primarybiliary cirrhosis and 25 ageand se~matched controls by simpledouble immunodiffusion in a polyacrylamide gel. 75 IqM was detectedin a quarter of the patients and~_none of the controls.The presence of 75 IgM was related to the elevation of totalIgM as measured by the radial immunodiffusion techniques.Patients with 75 IgM had significantly higher levels of cryo-globulins and immune complexes in their sera than 75 IgM-negativepatients. In addition, serum alkaline phosphatase concentrationswere more elevated in the 75 IgM-positive patients than in the75 IgM-negative patients,zeflecting more extensive bile ductdamage. The presence of monomeric (75) IgM as well as otherdifferences in the IgM molecule may be significant for t~e patho-genesis of primary biliary cirrhosis.