Gamma interferon is produced by human natural killer cells but not T cells during Staphylococcus aureus stimulation

Gamma interferon (IFN-gamma) production from cultured human peripheral blood mononuclear cells was studied during stimulation with Staphylococcus aureus Cowan I or S. aureus Wood. IFN-gamma was specifically produced from CD16+ natural killer (NK) cells under stimulation by S. aureus Cowan I or Wood because these strains (i) induced IFN-gamma production exclusively from CD3-, CD4- CD8-, and CD16+ cells and (ii) induced CD69 and interleukin 2 (IL-2) receptor alpha expression on CD16+ cells without simultaneously augmenting CD71 or IL-2 receptor alpha on T cells. The effects of biological agents on the induction of S. aureus-induced IFN-gamma production paralleled those of S. aureus-induced CD69 expression on CD16+ cells: IL-2, IFN-alpha, and indomethacin augmented the S. aureus-induced IFN-gamma production, whereas IL-4, transforming growth factor beta 1, prostaglandin E2, and dexamethasone inhibited it. However, IFN-alpha was unique in that it did not induce IFN-gamma production from NK cells while it simultaneously augmented CD69 expression on NK cells, suggesting a unique pathway in the activation of NK cells. Thus, we may conclude that S. aureus-induced IFN-gamma production appears to faithfully represent NK cell function within peripheral blood mononuclear cells.