Abstract
Peripheral blood mononuclear cells from 45 children, aged 1 to 19 years were evaluated for natural killer cell cytotoxic activity against K-562 erythroleukemic cells, The results of a
51Cr release assay demonstrated that the NK cell activity of normal children is dependent on age and sex. Younger females, aged 1 to 9 years, were more reactive than elder females aged be-tween 10 and 19 years (P<0.001). Males aged 1 to 19 years were less reactive than adults (0.02<P<0.05). Among children, the levels of NK cell activity were significantly greater in females than in males (0.001<P<0.01). In contrast, among elder children, the levels of NK cell activity were significantly greater in males than in females (0.01<P<0.02). The NK cell activity of elder female children was 60% and 59% that of the elder male children, at the two E:T ratios of 50:1 and 100:1, respectively.
