Detection of infectious mononucleosis heterophil antibody by a rapid, standardized enzyme-linked immunosorbent assay procedure

A rapid, specific, sensitive, standardized, a reproducible enzyme-linked immunosorbent assay (ELISA) procedure has been developed for detecting the heterophil antibody associated with infectious mononucleosis (IM). The IM heterophil antibody used for the solid phase was purified from bovine erythrocyte stroma. The test uses heavy-chain-specific anti-immunoglobulin M (IgM) labeled with alkaline phosphatase and three 10-min incubations. The quantitative results correlated well with horse erythrocyte agglutination titers. Absorption tests confirmed the specificity of the ELISA reactions for IM heterophil antibodies. Neither very high levels of IgM in myeloma sera nor high levels of rheumatoid factor caused false-positive reactions. A number of probable IM cases were encountered which positive by ELISA but negative by the horse erythrocyte slide agglutination test. Absorption studies indicated that these were true-positives for the IM heterophil antibody. The IM heterophil antibodies were confirmed to be predominantly of the IgM class, but moderate proportions of the IgM class were sometimes encountered.