Detection of specific immunoglobulin M antibodies to cytomegalovirus by using monoclonal antibody to immunoglobulin M in an indirect immunofluorescence assay.

The detection of immunoglobulin M (IgM) antibodies to cytomegalovirus-induced late antigens by an indirect immunofluorescence assay was improved by the use of monoclonal antibodies to human IgM. Nonspecific background fluorescence was absent, facilitating the reading of the slides and the detection of a specific fluorescence reaction in sera with low levels of specific IgM. Moreover, the indirect immunofluorescence assay with monoclonal antibodies to IgM proved more sensitive than the indirect immunofluorescence assay with polyclonal antibodies to IgM. The absorption of human sera on staphylococcal protein A avoided false reactions due to the presence of rheumatoid factor and high levels of specific IgG in test sera.