Defective elimination of C3b/iC3b-coated autologous erythrocytes in patients with primary biliary cirrhosis, alcoholic cirrhosis, and ulcerative colitis.

Delayed in vivo elimination of autologous erythrocytes coated with immunoglobulin G has been reported in autoimmune and inflammatory gastrointestinal diseases. Our aim was to elucidate whether impairment of the macrophages was restricted to the Fc receptors of the reticuloendothelial system or whether complement receptors were also affected. We studied elimination by complement receptors of autologous erythrocytes coated with fragments of C3 and C4 in patients with primary biliary cirrhosis, ulcerative colitis, and alcoholic cirrhosis. Impaired function was seen in all patient groups as compared with function in normal subjects, both concerning the mean half-life of the injected cells and the total number of eliminated erythrocytes. Neither of these parameters correlated with the levels of C3 fragments bound to the injected autologous erythrocytes. This is the first report of defective complement receptor function in ulcerative colitis and alcoholic cirrhosis. Immunoglobulin G-dependent elimination of erythrocytes was confirmed to be lowered in all patient groups. The results suggest severe macrophage functional aberrations involving both complement receptors and Fc receptors as the basis of phagocytic defects in autoimmune/inflammatory conditions. In contrast, a general loss of macrophages might cause the functional loss in alcoholic cirrhosis.