Two-site ELISA for quantification of the terminal C5b-9 complement complex in plasma. Use of monoclonal and polyclonal antibodies against a neoantigen of the complex.

A quantitative ELISA procedure using monoclonal and polyclonal antibodies against neoantigens of the terminal C5b-9 complement complex has been developed. The ELISA was demonstrated to be both sensitive and reproducible. The normal range for C5b-9 determinations, defined as 2.5-97.5% interval of the values obtained in 76 healthy blood donors, was 3.12-10.3 AU/ml. The presence of rheumatoid factor did not affect the determination of C5b-9 as demonstrated by immunoabsorption studies.