A shared antigenic specificity of human large granular lymphocytes and precursors of NK-like and allospecific cytotoxic effector cells.

We describe here a new monoclonal IgG1 antibody, NK-9, which recognizes practically all large granular lymphocytes (LGL), the mediators of human NK activity. This antibody also reacts with an originally noncytotoxic, non-LGL lymphocyte population that contains precursors of the inducible NK-like and allospecific cytotoxicity in the blood. The NK-like effectors are also NK-9+. The results thus suggest a close precursor relationship of endogenous NK cells, NK-like cells, and allospecific CTL in the blood. NK-9 antibody does not crossreact with B cells, monocytes, or granulocytes or with any of a large panel of cultured cell lines tested, including T and B cell as well as null cell lymphoma-leukemia lines. It does not inhibit the functional properties of the positive cells. The antigens for NK-9 antibody on the cell surface have m.w. of 190, 200, and 220 kD, and at least the former two appear to be glycosylated. The non-LGL, noncytotoxic NK-9+ cells contain only the 190 kD antigen, but the other two appear concomitantly with the induced NK-like cytotoxic activity on the cells. The NK-9-detected antigens are retained after formaline fixation, and NK-9 antibody can thus be used to stain normal formaline-fixed, paraffin-embedded histologic sections.