CH50 complement test
Hemolysis assays (CH50 complement test or AH50) are the most commonly used for assessing the functional activity of the CP and AP of complement. The hemolytic assay for CP is based on the use of IgG antibody-coated sheep erythrocytes which are lysed in serum and diluted in a buffer containing Ca²⁺ and Mg²⁺. The results are usually expressed as the reciprocal dilution of serum needed to lyse 50% or 100% (CH50 or CH100, respectively) of erythrocytes. The functional activity (AH50) of the AP is similar to CH50 except that in the AH50 test of AP, guinea pig, rabbit or chicken erythrocytes are used as target cells and antibody-coated erythrocytes are lysed in serum and diluted in buffer containing only Mg²⁺.
