Interaction of collagen with serum complement: inhibition of complement-mediated hemolysis

Collagens from various vertebrate tissues were tested for their ability to consume complement (C) activity upon incubation in human serum or with isolated components of complement. 10 of 12 collagens tested had anticomplementary activity. The heat-denatured form of collagen, gelatin, was found weakly anticomplementary, but elastin was found inactive in the interaction with C. Inactivation of C is a reaction which is dependent on the time of incubation and the collagen concentration and partially dependent on the temperature of incubation. Most collagens depleted C from human serum in presence of cation chelators, EDTA and EGTA, whereas the large part of anticomplementary activity of soluble collagens obtained from rat skin was abolished in presence of EDTA. Evidence is presented that two different principles in collagens play a role in inactivation of C. A factor, contained in insoluble collagens and inhibitable by mild oxidation with periodate, inactivates C1 directly even in presence of chelating agents. Another principle, contained in soluble and insoluble collagen and resistant to periodate treatment, depletes C in serum by utilization of C via the alternate pathway (the C3 shunt).