Natural killer cell activity in hepatocellular carcinoma. In vitro and in vivo responses to interferon.

We have measured natural killer (NK) cell activity in patients with hepatocellular carcinoma (HCC) and have examined the effects of in vitro and in vivo administration of alpha-interferon (IFN) on NK cell activity. The NK cell cytotoxicity of HCC patients was significantly lower than that of patients with cirrhosis or healthy controls. Reduced NK cell cytotoxicity in HCC did not correlate significantly with either the serum alpha-foetoprotein concentration or the patient WHO performance grade. NK cell cytotoxicity in all groups could be increased by prior incubation of effector cells with IFN, but this was significant only in HCC patients, in whom 10 IU/ml of IFN increased NK cell cytotoxicity from 37 +/- 10% to 53 +/- 8% (effector to target ratio, 50:1, mean +/- SEM; p less than 0.05). Further increases in IFN concentration failed to increase NK cell activity further. NK cell cytotoxicity was measured immediately before and 24 h after 2.5 x 10(6) IU/m2 of IFN was given subcutaneously to four HCC patients. NK cell cytotoxicity rose from 27 +/- 9% to 61 +/- 5% (effector to target ratio, 50:1, mean +/- SEM; p = 0.05).