[The immunophenotypic characteristics of two functionally different natural killer cell subpopulations in peripheral...

NK cell cytotoxicity and immunophenotypic characteristics of activated natural killer (NK) cells after co-incubation with K562 target cells in women were investigated. An increase in CD69, HLADR, CD95 expression on target-activated NK cells was demonstrated. Conversely, CD62L expression in NK cells after activation was decreased. The results showed that only a part of NK cells after incubation with K562, became CD69 positive. Moreover, even after lowering of "efector - target" ratio and extensions of time of stimulation, the amount of CD69+NK cells did not exceed 60% (50% +/- 1.7%). Expression of CD69, CD95 and HLADR on NK cells before coincubation didn't correlate with NK cytotoxicity. However, size of population of activated CD69+ NK cells (after stimulation) was correlated with NK cytotoxicity. We also found that the activation capacity after cocultivation with K562 cells is related to loss in CD62L on NK cell's surface. Only CD62L(neg) and less CD62L(low)NK cells had the ability to be activated with K562. In conclusion, we demonstrated that incubation with K562 target cells enhanced the expression of CD69 on the major part of NK cell population and the size of CD69+NK cell population is strongly correlated with NK cytotoxicity.