Quantitative studies of the secretion of complement component C3 by resident, elicited and activated macrophages. Comparison with C2, C4 and lysosomal enzyme release.

To quantitate the secretion of complement component C3 by guinea pig peritoneal macrophages an enzyme-linked immunosorbent assay was developed. C3 secretion was studied in resident, elicited and activated macrophages and compared with release of hemolytically active C2 and C4, as well as the lysosomal enzyme beta-D-2-acetamido-2-deoxyglucosidase. Resident macrophages secreted about 6 ng C3/10(6) cells/h into culture supernatants over a period of 12 h. Corynebacterium parvum-activated cells were found to secrete 3 times that amount at nearly constant rates. There was a stepwise increase in secretion of functional C2 and C4 when comparing resident, elicited and activated macrophages; secretion was 2--4 times higher in activated than in resident cells.