[Inhibition of NK activity by oses: effect of interleukin 2 (author's transl)]

Several sugars can strongly inhibit the natural cytotoxicity (NK) exhibited by peripheral blood lymphocytes (PBL) against tumour cells. The inhibition of NK cytotoxicity mediated by mannose, glucose, galactose and saccharose was tested in human PBL. All these sugars significantly blocked (P less than 0.01 at 50 mM concentration) the NK cytotoxicity. The blocking is dose-dependent in a linear pattern. The sole preincubation of the attacking (NK) population is required for inhibition of cytotoxicity; no influence of the sugars were noticed on the K562 alone. In contrast, the NK cytotoxicity of PBL primed in mixed lymphocyte reaction and further cultured in presence of conditioned medium (CM), showed, aside of a clear increase (average 40% increase of specific 51Cr release, P less than 0.05) a full insensitivity to the tested sugars. Phytohaemagglutinin (PHA), interferon (IF) and an interleukin 2 (Il2) are contained in the CM. We showed that neither the PHA nor the IF preincubation of the cells can induce the insensitivity of NK for the sugars, thus our data strongly suggest that Il2 is implicated in the sugar insensitivity of the cytotoxicity of lymphocytes cultured with CM.