Detection of a Negative Correlation between NK Cell Cytotoxicity and IFN Production in Healthy Individuals.

As an extension of our investigation of the mechanisms of regulation of NK cell activity we have compared the integral parameters of NK cell cytotoxicity (IPC) and IFN production (IPIP) measured as the square of the area under the cytotoxic and IFN titer functional curves. They were compared with the parameters obtained by the standard effector : target cell (E:T) ratio method. The calculations were done in groups of healthy individuals, PBL of which are distinguished by the levels of NK cell cytotoxicity and IFN production measured in the reaction of natural cytotoxicity. For the calculation of the difference, we used data from individuals with values of the IPC and IPIP higher or lower than the mean values. It has been shown that the "changes" in IPC and IPIP are not proportional. The variations in the NK cytotoxicity were 13-45%, while the differences in IFN titer were 38-69% as compared to the mean values. This analysis revealed a negative correlation between the variations corresponding to some E:T ratios. The correlation coefficients varied between -0.07 and -0.28, suggesting a weak negative association between the compared parameters. Thus, the approach used in this work helped us to develop experimental conditions that revealed a negative correlation between NK cell cytotoxicity and IFN production by normal human PBL.