[Natural cytotoxicity in complex of cell interactions]

The paper summarizes the results of studies on the mechanisms and factors that do prevent natural killer (NK) cells from their cytotoxicity against the body's own cells. The findings support the fact that three-level mechanisms are involved in the protection of the body's cell from NK cell damage. The mechanisms of the first endogenic level are ensured by the factors which form a regulatory balance in the complex of NK cell responses. Those of the second endogenic level are ensured by the factors that participate in the transfer and exchange of metallic cations in the cell microenvironment. The third (exogenous) level mechanisms have been found in the study of the lymphocytic functions of cyanobacterial exometabolites and their derivatives from tap water probes. The products tested are able to block the generation of the free oxygen radicals utilized by NK cells in their lethal shock. A limitation of NK cell cytotoxicity seems to an important condition for non-cytotoxic regulatory NK cell interactions with immune and other cells.