Sensitive one-step haemolytic assays of the fourth (C4) and fifth (C5) components of the human complement system

Abstract

In this paper, we describe two simple «one-stepå methods to assay the C4 and C5 haemolytic activities of human complement. These methods required fresh normal human sera immunochemically depleted of C4 or C5 components of the complement system. These sera, called R4 and R5 respectively, were prepared by affinity chromatography on monospecific anti-C4 Sepharose-4B or monospecific anti-C5 Sepharose-4B. Resins were washed with high-ionic strength solution containing 20% saccharose, which gave this method a very high specificity. These reagents were successfully used in the detection and quantification of C4 and C5 in all preparation steps as well as in normal and pathological sera. Two different kinds of haemolytic assays were developed and optimized: a haemolytic tube assay and a haemolytic agarose plate assay.