[THE TECHNQUE OF FLOW CYTOMETRY IN EVALUATION OF NK-CELLS AND THEIR ACTIVITY]

The review presents main characteristics of human natural killer cells (NK-cells), their phenotype and methods of detection of functional activities using flow cytometry. The NK-cells play important role in inherent and adaptive immunity against infections and tumors. Initially these cells were characterized on the basis of capacity to lyse malignant and infected cells without preliminary sensibilization or immunization. The human NK-cells have phenotype CD3-CD56+CD16+ and can be separated in two subpopulations depending on level of expression CD56. The CD56 bright NK-cells predominantly participates immuno-regulation producing cytokines. The CD56dim NK-cells predominantly have cytolytic activity. The NK-cells mediate destruction of infected and neoplastic cells through several effector mechanisms: by means of perforins/granzyme containing granules, receptors of apoptosis, antibody-depended cellular mediated cytotoxicity. The cytotoxicicty of NK-cells and production of cytokines provide regulatory role of NK-cells as important participants of adaptive immune system. The NK-cells are fitted with various receptors stimulating and inhibiting their activity. The activation of NK-cells depends on balance between inhibiting and activating receptors. The activation of NK-cells depends on balance between inhibiting and activating receptors. "The golden standard" of detection offunctional activity of human NK-cells is a test of releasing of radioactive chrome from target cells. To apply this technique in clinical practice is not an easy task because of difficulties of utilization of radioactive waste products, short half lifetime, expensiveness and complicated standardization. The article presents cyto-fluorimetric techniques for clinical detection of activity of NK-cells. These techniques permit to avoid a number of problems related to application of radioactivity. They also are fast and can be standardized.