A rapid immunofluorescent procedure for the detection of specific IgG and IgM antibody in sera using Staphylococcus aureus and latex-IgG as absorbents.

Sera from adults with toxoplasmosis and individuals with anti nuclear antibodies were examined for the presenceof specific IgM and IgG antibodies and for the occurrence of anti-immunoglobulin ("RF") activity both before and after absorption with freeze-dried preparations of protein A-containing Staphylococcus aureus. Such absorption removed most of the IgG present in sera without interfering with the detection of IgM antibody by immunofluorescence, but was relatively ineffective in the removal of "RF". "RF" activity, demonstrable by slide agglutination, was removed by absorption with latex coated with IgG. In order to prevent the possibility of false positive IgM staining in immunofluorescence tests, it is concluded that sequential absorption with latex-IgG particles and protein A-positive staphylococci is essential. Such absorption is technically simple and can be performed on small volumes of serum.