Human peripheral mononuclear cell responses to UV damage are affected by radiation-induced changes in plasma

To evaluate the effects of environmental or therapeutic stress adequately, it is important to study cells or tissues under conditions that simulate as closely as possible the in vivo environment. To determine whether the responses of irradiated cells are significantly affected by radiation-induced changes in plasma, human mononuclear cells were isolated from peripheral blood and cultured in their autologous plasma. Freshly isolated cells were irradiated in phosphate-buffered saline. The plasma was irradiated separately. Irradiation of the plasma suppressed mitogen-induced DNA synthesis in unirradiated cells. For cells that were UV-damaged and subsequently stimulated with mitogen, DNA synthesis was enhanced by irradiation of the plasma. Medium in which irradiated cells had previously been incubated enhanced DNA, synthesis in unirradiated cells that had been mitogen stimulated but did not affect the UV-induced shutoff of DNA synthesis in replicating cells or unscheduled DNA synthesis in irradiated cells.