Comparison of multiple rosetting assays for detecting antibody reactivity of different immunoglobulin classes against surface antigens of benign and malignant tissue culture cells.

Four serological assays for detection of antibody reactivity against surface antigens of benign and malignant cells have been evaluated. In all four assays, antibody attached to the surface of a target cell is detected by a rosette of indicator red blood cells. Of the four assays (antibody mixed hemadsorption assay, immune adherence assay, anti-C3 mixed hemadsorption assay and protein A assay), the anti-C3 mixed hemadsorption assay showed highest sensitivity. By using purified IgM and IgG fractions we could demonstrate that, except for the protein A assay, all assays show reactivity both with IgG and IgM. Protein A assay detected only the IgG fraction, with high sensitivity. The optimization of the four assays is described and the importance of using multiple assays is emphasized.