ABSTRACT
A description of the first labeling of antibodies and, indeed, the first immunocytochemical staining was published by John Marrack in 1934. In the indirect immunocytochemical technique, the primary antibodies are used unlabeled. Use of monoclonal antibodies could entirely replace the labeled antigen detection methods. Controls in all of the labeled antigen detection techniques include elimination of the various antibody layers to prove that the binding of antigen to tissues is immunological. Protein A-ferritin conjugates also have been exploited using an erythrocyte model system, and C. Miller et al. have conjugated hemocyanin to protein A for use in ultrastructural immunocytochemistry. Besides colloidal gold, ferritin is the most popular particulate marker for immunoelectron microscopy. Immunocytochemical applications extend from conventional immunofluorescence and light microscopy, fluorescence-activated cell sorting to scanning electron microscopic. Hybrid antibodies can be used for interesting and potentially very useful immunocytochemical localizations.
