INHIBITION OF IMMUNOGLOBULIN PRODUCTION IN HUMAN NAMALWA CELLS AND RAT SPLEEN LYMPHOCYTES BY BILE-ACID

The effects of bile acids on the proliferation and IgM production of h uman lymphoblastoid Namalwa cells and on the Ig production of rat sple en lymphocytes were examined. Among the free bile acids examined, two dihydroxy bile acids, CDCA and DCA, inhibited the proliferation of Nam alwa cells and Ig production by rat spleen lymphocytes at concentratio ns above 20 mu g/ml, while the inhibitory effect of a trihydroxy bile acid, CA, was much weaker. The inhibitory effects of their conjugated bile acids were weaker than those of the free ones, and the DCA deriva tives were more toxic than the CA ones. These results suggest that dih ydroxy bile acids were more toxic to Ig production by spleen lymphocyt es than trihydroxy ones. The effect of bile acids on Ig production by the lymphocytes was examined in the presence of such mitogens as LPS, PHA, ConA, and PWM. As a result, TDCA inhibited their IgG and IgM prod uction at 200 mu g/ml independently of the mitogen addition, while TCA was almost ineffective. It thus seems likely that the bile acid inhib its the Ig production by spleen lymphocytes through non-specific inhib ition of the both T and B cell functions.