IL-12 or IL-4 prime human NK cells to mediate functionally divergent interactions with dendritic cells or tumors.

In the course of inflammatory responses in peripheral tissues, NK cells may be exposed to cytokines such as IL-12 and IL-4 released by other cell types that may influence their functional activities. In the present study we comparatively analyzed purified human peripheral blood NK cells that had been exposed to either IL-12 or IL-4 during short (overnight) incubation. We show that although IL-12-cultured NK cells produced abundant IFN-gamma, TNF-alpha, and GM-CSF in response to stimuli acting on the NKp46-activating receptor, IL-4-cultured NK cells did not release detectable levels of these cytokines.

DNase I behaves as a transcription factor which modulates Fas expression in human cells.

DNase I is the major nuclease present in biological fluids and is ubiquitously expressed in mammalian tissues. It is responsible for the removal of DNA from nuclear antigens, and consistently with this function, DNase I-deficient mice show features of autoimmunity. The enzyme seems also to be involved in apoptosis (programmed cell death).

CD59 is physically and functionally associated with natural cytotoxicity receptors and activates human NK cell-mediated cytotoxicity.

Triggering of cytotoxicity in human NK cells is induced by the combined engagement of several triggering receptors. These include primary receptors such as NKG2D and the natural cytotoxicity receptors (NCR) NKp30, NKp46 and NKp44, while other molecules, including 2B4, NTB-A and NKp80, function as co-receptors. As reported in the present study, during an attempt to identify novel NK receptors or co-receptors, we found that CD59 functions as a co-receptor in human NK cell activation; engagement of CD59 by specific mAb delivers triggering signals to human NK cells, resulting in enhancement of cytotoxicity.