Abstract
The detection of cell surface antigens is the most familiar application of flow cytometry in clinical immunology. Rapid advances in immunocytochemical applications of monoclonal antibodies, which may now be regarded as “true” reagents in the clinical laboratory, have made possible the immunological characterization of various tumors (1–3) and the classification of cells of the immune system (4–6). This extensive immunological characterization was virtually unattainable a few years earlier.