Abstract

The familial occurrences of biochemical and immunological abnormalities and histocompatibility antigens were studied in 18 healthy first-degree relatives of patients with primary biliary cirrhosis (PBC) in two families. In each of these two families, there were two members who suffered from PBC. All relatives had normal serum aspartate aminotransferase, alkaline phosphatase, bilirubin, total cholesterol, and immunoglobulins except the two, who had a mild elevation of alkaline phosphatase without cholestasis. Autoantibodies were present in some relatives; five (28%) for antithyroglobulin antibody and antithyroid microsomal antibody, one (6%) for antimitochondrial and antinuclear antibody, and one (6%) for rheumatoid factor. Abnormalities of T or B lymphocytes in peripheral blood were detected in two (11%) relatives. Impairment of concanavalin A-induced lymphocyte transformation determined by ethidium bromide fluoroassay was found in seven (39%) relatives, although an abnormal response for phytohemagglutinin was detected in none of the relatives. The HLA haplotypes were not necessarily associated with positive autoantibodies or impaired concanavalin A-induced lymphocyte transformation in these families. These findings suggest that impairment of concanavalin A-inducible lymphocytes (mainly suppressor T cells) is one of the contributing factors in the development of PBC.