Studies on the possible involvement of complement component C3 in the initiation of acid hydrolase secretion by macrophages.

Complement component C3 has been detected on the plasma membranes of mouse peritoneal macrophages by using an immunoperoxidase technique in conjunction with transmission electron microscopy. Evidence that such cell surface-associated C3 might be the trigger for lysosomal enzyme discharge was sought initially by exposing macrophage monolayers to anti-mouse C3 F(ab')2, and later, by treating cells with the antibody fragment before two potent secretagogues (methylamine and zymosan particles). Both methods, however, failed to demonstrate a role for cell surface-associated C3 in the initiation of enzyme secretion.