A simplified method of measuring the complex-release activity (CRA) of complement using peroxidase (PO) as an antigen in the immune complex was studied. PO-anti PO rabbit IgG immune complex (PO-IC) was solubilized principally via the alternative pathway in the sera. When substrates, H(2)O(2) and 5-aminosalicylic acid, were added to solubilized PO-IC, absorbance of the mixture at O.D. 450nm increased with the amount of complement in a dose-dependent manner. The CRA of the complement in the sera was shown by the absorbance of the mixture. The CRA in various sera correlated with CH50. The CRA via the alternative pathway (ACRA) in sera also correlated with CRA, CH50 and ACH50.The above results indicate that this method of measuring the complex-release activity of complement using peroxidase as an antigen is simple and useful.
alternative complement pathway