Abstract
Colloidal gold was used as a marker for the light microscopic detection of lymphocyte cell surface antigens with monoclonal antibodies. Suspensions of peripheral blood leukocytes were first incubated with monoclonal mouse antibodies and then with colloidal gold-labeled goat anti-mouse antibodies. The cells were fixed and cytocentrifuge preparations or smears were made. Granulocytes and monocytes were then labeled by the cytochemical staining of their endogenous peroxidase activity. Lymphocytes reacting with the monoclonal antibody had numerous dark granules around the surface membrane. With electron microscopy, these granules appeared as patches of gold particles. This immunogold staining method proved to be a reliable tool for the enumeration of T-lymphocyte subpopulations in peripheral blood. The results were almost identical to those obtained with immunofluorescence microscopy. The procedure can also be applied on small volumes of capillary blood. This constitutes a good microtechnique for the determination of lymphocyte subsets in children.