Antilymphocyte antibodies:an approach to dissecting the heterogeneity of the immune system.

Antilymphocyte antibodies can be used to dissect the lymphocyte populations and subpopulations. In the mouse, at least seven gene loci govern the expression of allo-, hetero-and autoantigens at the surface of T-lymphocytes. The antisera, especially the alloantisera, permit definition of the differentiative state of cells and discriminate between subsets of T-cells with different functions. Less is known about human T-lymphocyte differentiation antigens and their genetic determinism. However, heterologous antisera specific for human T-cells have been prepared and their use has been of help in studying this cell population. The antigens recognized by such antisera are present at a higher concentration on thymocytes than on peripheral blood T-lymphocytes. They appear at the surface of bone marrow T-cell precursors after a short incubation with thymic factors. Such markers of T-lymphocytes in various stages of differentiation and the study of in vitro differentiation from precursor cells have already proven to be valuable tools for clinical investigation, especially in the realm of immunodeficiency diseases.