Analysis of cell-surface markers with staphylococcal protein A: fluorescence studies on mammalian lymphoid...

Membrane antigens including different classes of immunoglobulins, transplantation antigens, beta2-microglobulin, T lymphocyte specific antigens, and virally determined surface components were investigated using fluorescein-labeled Staphylococcal protein A in combination with cytofluorometric studies. Lymphocytes of seven species: mouse, rat, guinea pig, pig, cow, monkey, and human, and of ten human lymphoma-derived lines were tested. Analysis of the differential expression of surface markers revealed a reproducible reaction of protein A with cell-surface Fc of IgG actively produced by lymphoid cells from human, monkey, guinea pig, and pig, and with passively attached IgG molecules in the form of antibodies, directed against cell surface antigens of all lymphoid cells tested. No surface Ig was detected on so-called T lymphocytes. The distribution of cell-bound Ig density among surface Ig-positive cells was found to be different depending upon the origin of the cells with regard to lymphoid organ; it was parallel among the lymphoma lines tested and on peripheral blood cells from human, monkey, and pig, although large variations in fluorescence intensity among individual cells and among the different lines were recorded. Beta2-microglobulin determinants were found equally well on enriched human T and B cells. Transplantation, and T lymphocyte-specific antigens were detected on the majority of the lymphoid cells and on a restricted population respectively.