A human natural killer cell-associated antigen defined by monoclonal antibody anti-Leu (NKP-15): functional and two-color flow cytometry analysis.

A monoclonal antibody, anti-Leu 11a (NPK-15), was generated against human large granular lymphocytes (LGL). Anti-Leu 11a reacted with the majority of Percoll gradient-enriched LGL cells, a subpopulation of peripheral blood lymphocytes (PBL) approx (approximately 10-20%), and most granulocytes, but not with a significant number of monocytes, T lymphocytes, or erythrocytes. Cell sorting experiments demonstrated that the Leu 11a+ population encompassed essentially all functional natural killer (NK) cells in the peripheral blood. Two-color flow cytometry analysis of PBL populations stained with anti-Leu 11a and anti-Leu 7 revealed the existence of four distinct populations: Leu 11a-, 7+; Leu 11a+, 7-; Leu 11a+, 7+; and Leu 11a-, 7-. The Leu 11a+ population did not appear to include cells marked with the T cell-associated antigens Leu 1, Leu 2, or Leu 3. The existence of a cell surface antigen common to granulocytes and NK cells, which is capable of distinguishing subpopulations of Leu 7+ cells, provides a useful probe to analyze the nature of the NK lineage.