HUMAN PERIPHERAL MONONUCLEAR CELL RESPONSES TO UV DAMAGE ARE AFFECTEDBY RADIATION-INDUCED CHANGES IN PLASMA

To evaluate the effects of environmental or therapeutic stress adequat ely, it is important to study cells or tissues under conditions that s imulate as closely as possible the in vivo environment. To determine w hether the responses of irradiated cells are significantly affected by radiation-induced changes in plasma, human mononuclear cells were iso lated from peripheral blood and cultured in their autologous plasma. F reshly isolated cells were irradiated in phosphate-buffered saline. Th e plasma was,irradiated separately. Irradiation of the plasma suppress ed mitogen-induced DNA synthesis in unirradiated cells, For cells that were UV-damaged and subsequently stimulated with mitogen, DNA synthes is was enhanced by irradiation of the plasma, Medium in which irradiat ed cells had previously been incubated enhanced DNA synthesis in unirr adiated cells that had been mitogen stimulated but did not affect the UV-induced shutoff of DNA synthesis in replicating cells or unschedule d DNA synthesis in irradiated cells.