Because of elevated level of biologically active middle wave ultraviolet irradiation (280-320 nm) in biosphere, problem of cell mechanisms of its action is very urgent for medicine and ecology. Cells providing the immune homeostasis of organism are of special interest in this respect. Analysis of the processes at the level of cell membranes and main regulatory systems in cell functions (one of these systems - system of intracellular pH-regulation) is very important in the studing of this problem.

We studied the effects of middle-wave ultraviolet irradiation on some types of immunocompetent cells using probe microfluorimetry of single cells. The state of plasma membrane, activity of intracellular hydrolytic ferments, and level of intracellular pH, which is one of the important factors of regulation of cell functions, were studied. It was found that irradiation doses more than 6 J/cm² lead to disturbances in cell membrane integrity and cells death. Radiation in doses more than 0.25 J/cm² lowers the intracellular pH, hydrolytic activity of cell content and, significantly, cell survival 36 h after ultraviolet action. Meanwhile, radiation in lower doses leads to some increase in intracellular pH and activity of esterases. However, these changes do not lead to increase in cell proliferative activity in further.

Thus, we establish the general regularities of influence of middle-wave ultraviolet irradiation on various types of immunocompetent cells. The obtained data suggests the possibility of modification of some cell parameters by low doses of ultraviolet. Besides, the participation of system of intracellular pH-regulation in processing of effects of radiation was found.