A comparison of peroxidase- and fluorochrome-conjugated antisera for the demonstration of surface and intracellular antigens

The preparation of highly effective peroxidase-labeled F(ab′)₂ antibody fragments allowed the development of direct immunoperoxidase techniques analogous to existing immunofluorescent methodology. Peroxidase-labeled and rhodamine-labeled antisera were used in parallel experiments to demonstrate lymphocyte surface immunoglobulin, B-lymphocyte alloantigens and the intracellular immunoglobulin of cultured lymphoblastoid cells and mitogen-stimulated peripheral blood lymphocytes. Immunoperoxidase and immunofluorescence were comparable in specificity and sensitivity. Intracellular immunoglobuin was demonstrated by direct immunoperoxidase in formalin-fixed, paraffinembedded bone marrow biopsies of patients with multiple myeloma. Current immunoperoxidase methodology was modified to avoid nonspecific interference by endogenous peroxidase activity and the tissue affinity of peroxidase. Immunoperoxidase was found to be a reasonable alternative to immunofluorescence for lymphocyte analysis, offering the advantages of permanent slide preparations, improved cytomorphologic detail, routine light microscopic examination, and application to fixed tissue sections, where immunofluorescence is unsuccessful.