Measurement of C9 concentrations using an immunochemiluminometric assay.

A 2-site immunochemiluminometric assay is described for the measurement of complement component C9 concentrations in biological fluids as an aid in the diagnosis and management of immune-based diseases. The assay utilises 2 monoclonal antibodies one of which is labelled with a chemiluminescent acridinium ester and one of which is covalently coupled to reprecipitated aminoaryl cellulose. The incubation time is 1 h with simultaneous reagent addition. The working range of the assay is 10-2500 micrograms/1 at CVs less than or equal to 10% and the results are in excellent agreement with those of an immunoradiometric assay. The assay exhibits superior performance to other immunochemical and immunoassay techniques and has the advantage of using stable, non-radioactive reagents.