Enzyme immunoassay for factor VIII-related antigen.

I describe a simple enzyme-linked immunosorbent assay (ELISA) for the quantitation of Factor VIII-related antigen in plasma with use of commercially available peroxidase-labeled antiserum and solid-phase support. Regression analysis of 85 plasma samples analyzed by this technique (y) and by a commonly used electroimmunoassay (Anal. Biochem. 15: 45-52, 1966) (x) gave the equation y = 0.223 + 0.77x (r = 0.973). The present method was also compared with enzyme immunoassay in which a phosphatase-labeled antiserum prepared in our laboratory was used; the correlation between the two assays was very good. The simplicity and specificity of the ELISA technique should make it a useful alternative to the more difficult and time-consuming Laurell method.