Surface antigens on mouse natural killer cells: use of monoclonal antibodies to inhibit or to enrich cytotoxic activity

In studies using monoclonal antibodies to cell-surface antigens we have identified 2 new antigens (H11 and 7.2) expressed on mouse NK cells. These are shared with T cells but not B cells. We have also shown that NK cells express T200 but lack detectable ThB or Lyt-1. The T200 and H11 surface molecules were implicated in the mediation or regulation of natural killing; monoclonal antibodies to T200 and H11 inhibited natural killing when added to the cytotoxicity assay but did not interfere with T cell cytotoxicity against the same target. The inhibitory effect of anti-T200 is consistent with recent evidence showing that antibodies to the Ly-5 polymorphic determinant on T200 block natural killing. The H11 determinants is on a different molecule. The absence of Lyt-1 and ThB on NK cells permitted development of a rapid and simple method for separating NK cells from T cells and B cells. Spleen cells incubated with rat monoclonal antibodies to Lyt-1 (on all T cells) and ThB (on all B cells) were 95% removed by adherence to Petri dishes coated with antiserum to rat immunoglobulin. The natural killer activity in the nonadherent population was enriched 16-fold.