Immunoglobulin classes in biopsies of autoimmune liver disease.

The immunological isotypes of plasma cell infiltrates in a series of consecutive liver biopsies from patients with chronic active hepatitis (CAH) and primary biliary cirrhosis (PBC) were determined immunohistochemically. The plasma cell infiltrate was more pronounced in PBC than in CAH. IgA and IgG isotypes predominated in CAH, and IgM and IgG in PBC. The expected predominance of kappa light chains was observed in every biopsy in PBC. However, in 8/14 CAH biopsies the plasma cells were predominantly lambda isotype. Lambda predominance was significantly associated with the presence of serum autoantibodies. These findings would suggest that different mechanisms operate in the pathogenesis of these two autoimmune liver diseases.