The fixation of heterocytophylic antibodies to macrophages.

Using autoradiographic methods, heterocytophylic antibodies were found to be fixed to the peritoneal macrophages of the guinea pig. The heavy chain of the IgG molecule was responsible for the cell fixation which was inhibited by the autologous Fc fragment. The fixation of heterocytophylic immune complex (rabbit antibody IgG + homologous OA antigen) was also inhibited by the Fc fragment. Only some of the macrophages (35-50%) were able, however, to fix immune complex.