Circulating immune complexes in primary biliary cirrhosis: interactions with lymphoid cells.

To evaluate the interactions between circulating immune complexes (CIC) and lymphoid cells in primary biliary cirrhosis (PBC), we determined (1) whether antibodies to lymphocytes in PBC serum, independent of CIC, could account for binding in the Raji cell assay for CIC and (2) whether CIC or other humoral factors in PBC serum could interact with lymphoid cells to alter their function. We found that three quarters of CIC positive PBC sera bound specifically to Raji cells via complement receptors, while only one quarter had antibodies to lymphoid cells or Raji cells devoid of complement receptors. We also demonstrated factors which inhibited cell-mediated cytotoxicity and suppressor cell activity in PBC sera; however, we found no correlation between the level and presence of CIC or of lymphocyte antibodies and the level or presence of these serum inhibitory factors. Thus, although the detection of CIC in PBC is not artifactual, the contribution of CIC and other serum factors to the other immunological aberrations in PBC remains to be elucidated.