Reconstruction of anti-leprosy drug depleted complement haemolytic activity by addition of zymosan-treated sera (a source of C142) and CratEDTA (a source of C3-C9).

This paper describes the mechanism of in vitro interaction of human serum complement system with anti-leprosy drugs (dapsone and clofazimine) and anti-lepra reaction drugs such as chloroquine. These drugs could inhibit the complement-mediated lysis of erythrocytes both via direct and alternative pathways, but only at hypertherapeutic doses. Attempts were made to restore the drug depleted complement-mediated lysis of erythrocytes by adding zymosan-treated guinea-pig sera (a source of C142) and also by adding Crat-EDTA sera (a source of C3-C9). Destroyed complement-mediated haemolytic activity by dapsone could be restored by early complement (C142) components, while complement-mediated haemolytic activity blocked by clofazimine could be regenerated by adding both late (C3-C9) and early (C142) complement component. However, chloroquine-mediated inhibition of the complement-mediated haemolysis activity could not be appreciably restored by adding both early and late complement reagents.