Determination of surface antigens on highly purified human NK cells by flow cytometry with monoclonal antibodies

Abstract

We examined highly purified populations of NK cells, T cells, monocytes, and PMN with a variety of monoclonal reagents presumed specific for T cells and monocytes. The enriched NK cells showed a pattern of reactivity that was distinct from that of the other 3 populations, sharing antigens with T cells but also sharing antigens with monocytes and/or PMN. A portion of the enriched NK cells expressed OKT8, OKT10, and Lyt-3 antigens that were reported previously as T cell-associated antigens, but no reactivity was seen with other T cell-associated antigens (OKT3, OKT4, OKT6, and OKT11). In addition a portion of the enriched NK cells were positive for OKM1, asialo-GM1, and Ia antigens, which are undetectable on typical T cells but are present on PMN and/or monocytes. By depletion of antigen-positive cells on antibody monolayers, it was found that the activity of the enriched NK population was associated mainly with cells reactive with OKT10, OKM1, and Lyt-3. Although considerable evidence exists to support the T lineage of NK cells, the sharing of some antigens by NK cells and monocytes has suggested a possible relationship of NK cells to cells of the monocyte lineage. A possibility certainly exists that NK cells are not in either T cell or monocyte lineages and may represent a separate lineage of lymphoid cells.