Expression of human T-lymphocyte antigens by natural killer cells.

Rabbit antisera against human T-lymphocyte and B-lymphocyte antigens (anti-HTLA and anti-HBLA, respectively) were used to characterize natural killer (NK) cells mediating spontaneous cell-mediated cytotoxicity for myelogenous leukemia cell line K562 as measured in a 51Cr-release assay. NK activity of lymphocyte suspensions was abrogated by incubation of the suspensions in anti-HTLA plus complement but not by incubation in anti-HBLA plus complement. The effect of anti-HTLA was due to removal of NK cells rather than antigen-antibody complex inhibition of NK cells inasmuch as lytic complement was necessary. The results indicated that NK cells were HTLA+-HBLA- and thus supported the concept that NK cells are T-cells.