Background/aims: There is as yet no explanation for the increased serum IgM level observed in patients with primary biliary cirrhosis.
Methodology: The serum IgM class anti-lipid A antibody was determined in patients with primary biliary cirrhosis using Elisa and Western blot techniques.
Results: Using enzyme-linked immunosorbent assay, we found the concentration of serum IgM class anti-lipid A antibody was the highest in 21 patients with PBC as compared to 29 patients with other liver diseases and 19 controls. Using western blotting, IgM class anti-lipid A antibody was detected as a clear band in patients with primary biliary cirrhosis. The level of this antibody correlated significantly (p < 0.005) with that of total IgM. Treatment with ursodeoxycholic acid improved not only the routine biochemical profile but also the level of IgM class anti-lipid A antibody (p < 0.005).
Conclusions: Since the lipid A plays a primary role in the biological activities of lipopolysaccharide (a component of gram-negative bacteria), bacterial antigen may participate in the elevation of serum IgM levels in patients with primary biliary cirrhosis. Ursodeoxycholic acid treatment may improve the cholestasis, and this may have altered the response to stimulation by gut derived bacterial antigens.