IgG and C3 receptors on polymorphonuclear leukocytes in phagocytosis. Role of C3-receptors in the attachement and ingestion phases

The role of IgG and complement (C3) receptors in the adhesion and ingestion phases of immune complexes by normal human polymorphonuclear leukocytes (PMN) were examined. The immune complexes were sheep red cells (E) sensitized with IgG (EA) or IgM antibodies plus complement (EAC'). Both types of receptor sites are involved in the adhesion phase. Moreover IgG receptors are primarily involved in the ingestion phase. Nevertheless even C3-receptors may be sufficient for complete phagocytosis. Even if EAC' adhesion was still high, C3-receptor specific phagocytosis decreased parallel with the amount of the complement used for EA19S sensibilization. The role of receptor sites on human PMN in adhesion and ingestion phases is discussed.