Inhibition of human NK cell and LAK cell cytotoxicity and differentiation by PGE2.

Activation of natural killer (NK) activity K562 target cells from nonadherent (NA) lymphocytes by interleukin 2 (IL-2) was inhibited marginally PGE2 (30-3000 nM). PGE2 did not effectively suppress the NK activity of IL-2-activated cells. The NK activation and acquisition of resistance to PGE2-mediated suppression of NK activity were dependent on protein synthesis. When NA cells were incubated with IL-2 for 3 or more days to generate lymphokine-activated killer (LAK) activity against Raji target cells, PGE2 only partially inhibited the activation of NK/LAK activity by an optimal dose of IL-2 (10 U/ml). The activation of NK/LAK activity by a suboptimal dose of IL-2 (0.1 U/ml) was inhibited by PGE2. When the NK/LAK activity of IL-2-activated cells was assessed in the presence or absence of PGE2, the LAK activity was more sensitive than the NK activity to PGE2-mediated suppression.