The mechanisms involved in the activation of human natural killer cells by staphylococcal enterotoxin B

The induction of enhanced natural cytotoxicity from human peripheral mononuclear cells by staphylococcal enterotoxin B (SEB) was examined. The activated killer cytotoxicity (AKC) was maximum at 16 hr with 1 mg/ml SEB. The precursor and effector cells of AKC were determined to be primarily CD5 negative, CD8 negative, CD16 positive cells. Monocytes and interleukin-1 played no role in the generation of AKC. However, a major role for interleukin-2 (IL-2) in AKC was shown by the inhibition of AKC when anti-IL-2 antibody or cyclosporin was added to the induction cultures. SEB rapidly induced the production of IL-2 from glass nonadherent cells by 6 hr and reached peak levels by 24 hr (162 U/ml). IL-2 induced by SEB in these induction cultures was preferentially produced by CD16 positive cells. Even though interferon-gamma (IFN-gamma) production was induced in these cultures, no role for IFN could be shown in SEB-induced AKC.