Alpha 2-macroglobulin: fast and sensitive analysis with monoclonal antibodies.

Monoclonal antibodies specific for human alpha 2-macroglobulin (alpha 2-M) have been produced. The antibodies were used in conjunction with commercially available rabbit antibody to alpha 2-M in a sandwich enzyme immunoassay. With incubation times of only 2 h with sample and 30 min with enzyme substrate, the useful range was 10-200 micrograms alpha 2-M per litre; longer incubation time increased the sensitivity. The intra-assay coefficient of variation (CV) was 5%; the inter-assay CV was 7%. The assay does not discriminate between native, methylamine-inactivated, and trypsin-treated alpha 2-M. The monoclonal antibodies are also useful for immunocytochemistry and for immunoprecipitation of alpha 2-M.