In vivo normobaric oxygen exposure depresses spleen cell in vitro Con A response. Effects of 2-mercaptoethanol and peritoneal cells.

Normobaric O₂ exposure decreased spleen cell (SC) response to T cell mitogen Con A. ³H-TdR incorporation of SC from O₂ exposed mice (O₂SC) compared to those of control mice (Air SC) decreased significantly after 72 and 87 h O₂ exposure. The dose response kinetics to Con A were identical in O₂SC or Air SC. Increasing SC number did not restore the response to Con A and the depressed hyperoxic effect was not related to suppressor cells in the spleen of O₂ exposed mice. Response of O₂SC to Con A was restored by the thiol compound 2-niercaptoethanol (2-ME). and the degree of restoration by 2-ME. was inversely proportional to the depressed response. Addition of intact peritoneal cells (PC) induced restoration within the same range as 2-ME. Restoration of the mitogenic response by 2-ME involved antioxidant properties and suggested that macrophages were functionally injured by O₂ exposure. In cases where mitogen response was highly depressed, restoration was only partial; in these conditions in vivo O₂ injury probably involved both macrophages and splenic T cells. The mechanisms of O₂ toxicity have been discussed in terms of free radical generation under hyperoxic conditions. [ABSTRACT FROM AUTHOR]