INTERFERON-GAMMA PRODUCTION BY NATURAL-KILLER (NK) CELLS AND NK1.1(-CELLS UPON NKR-P1 CROSS-LINKING() T)

Natural killer (NK) cells play an important role in immune response by producing interferon gamma (IFN-gamma) as well as exhibiting cytotoxi c function. IFN-gamma produced by NK cells has been suggested to be in volved in differentiation of T helper cells. On the other hand, the NK R-P1 molecule was recently identified as one of the important NK cell, receptors, and it recognizes certain kinds of oligosaccharides on tar get cells and triggers NK cells for cytotoxicity. In the present study , we found that NK cells produce great amounts of IFN-gamma upon cross -linking of the NKR-P1 molecule. In contrast, stimulation of NK cells with IL-2 induced proliferation without producing IFN-gamma. Similar t o NK cells, NK1.1(+) T cells also produced IFN-gamma upon NKR-P1 cross -linking. NK1.1(+) T cells produced IFN-gamma but not interleukin 4 (I L-4) upon NKR-P1 cross-linking, whereas they secreted both IFN-gamma a nd IL-4 upon T cell receptor cross-linking. These results indicate tha t NKR-P1 is a receptor molecule on NK and NK1.1(+) T cells that induce s not only cytotoxicity but also IFN-gamma production. Our findings pr ovide a new pathway for IFN-gamma production by NK and NK1.1(+) T cell s through NKR-P1 molecules; it may be essential for immune regulation.