Immunoperoxidase Slide Assay (IPSA) — A New Screening Method for Hybridoma Supernatants Directed against Cell Surface Antigens Compared to Other Binding Assays

Abstract A modified immunoperoxidase assay on microscope slides (IPSA) was adopted as a screening procedure for hybridoma supernatants with specificity for human lymphocyte subpopulations. The method proved. to be suitable for testing a large number of hybridomas with a minimum of cells and reagents. In addition, the slide-technique yields considerable information about the type and morphology of target cells. This allows a first differentiation between cell types in the assayed preparation, e.g. between lymphocytes and monocytes. Compared to indirect immunofluorescence, solid-phase radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) with intact cells as antigen, IPSA turned-out to be as sensitive as RIA and superior to indirect immunofluorescence and ELISA. Nevertheless, none of the assays used detected all supernatants binding to cells in the right manner and could, thus, be considered ideal. In our hands, the combination of RIA and IPSA proved to be an excellent system for screening procedures on lymphocytes.