[Natural killer activity in man under different experimental conditions]

The cytotoxic activity of natural killer (NK) cells against labelled with 3H-uridine target cells of standard human erythromyeloblast line K562 in 63 healthy donors was studied in 14-hr cytotoxic test. The cytotoxic reaction was realized in complete medium supplemented with different types of serum such as foetal calf serum (FCS), autologous or homologous sera in different schemes of incubation. It has been shown that NK cell activity was augmented by 50 per cent (p < 0.05) in the presence of homologous serum added to mononuclear cell suspension for 1 hr at 37 degrees C in comparison with the effect of FCS presence. Thus, the serum of healthy donors contains some factors which not only reflect an individual genotypic information of a donor, but also can be recognized by NK cells and significantly change the cytotoxic NK cell activity. The data obtained exclude possibility of using a homologous serum when positive controls for natural cytotoxic reactions are planned.