Protection by L-2-oxothiazolidine-4-carboxylic acid of hydrogen peroxide-induced CD3ζ and CD16ζ chain down-regulation in human peripheral blood lymphocytes and lymphokine-activated killer cells

Abstract We investigated whether l -2-oxothiazolidine-4-carboxylic acid (OTC) [in the form of Procysteine ® , kindly donated by Transcend Therapeutics] could protect peripheral blood lymphocytes (PBL) and lymphokine-activated killer (LAK) cells from CD3ζ and CD16ζ chain down-regulation induced by H 2 O 2 produced by lipopolysaccharide (LPS)-activated autologous monocytes. OTC is known to enhance glutathione production in cells in which glutathione was depleted by reactive oxygen species. Our data showed that OTC induced a significant increase in CD3ζ and CD16ζ chain expression in peripheral blood lymphocytes and LAK cells, respectively, pretreated for 12 hr at 37°. Moreover, OTC significantly protected peripheral blood lymphocytes and LAK against decreased ζ chain expression induced by lipopolysaccharide-activated monocytes or the addition of H 2 O 2 to the culture medium. Our experiments thus suggested that alterations in signal-transducing molecules, such as decreased CD3ζ and CD16ζ expression observed in cytotoxic T lymphocytes and LAK cells in response to oxidative stress, could be prevented by the use of OTC.