THE MODULATION OF IL-2 DEPENDENT PROLIFERATION OF CTLL-2 CELLS BY 2-METHYL-THIAZOLIDINE-2,4-DICARBOXYLIC ACID

It is known that cysteine and other thiol compounds are able to modula te the immune response. The extracellular concentration of cysteine wa s shown to determine the intracellular level of glutathione (GSH). Thu s cysteine, by enhancing GSH production, is able to affect some T-cell functions like IL-2 dependent cell proliferation and the generation o f cytotoxic T Cells. However, physiologically blood plasma cysteine is maintained at a very low concentration. The use of cysteine as a ther apeutic compound in vivo is strongly limited due to its cytotoxicity. Recent studies demonstrate that N-acetyl-cysteine (NAG) as well as a v ariety of thiazolidine derivatives (TDs), which are the products of th e reaction of L-cysteine with carbonyl compounds, could serve as a 'de livery' system for cysteine into the cell. In the present study, we ha ve shown that 2-methyl-thiazolidine-2,4,-dicarboxylic acid (CP), the p roduct of condensation of L-cysteine and pyruvate, strongly increases the proliferation of one particular cell line, IL-2 dependent CTLL-2 c ells. We have also shown that this compound significantly increases th e intracelullar level of non-protein sulfhydryls (NPSH), but we did no t find any correlation between NPSH levels and cell viability and prol iferation. In contrast to CP, free cysteine showed its toxic propertie s by affecting cell viability of different cell lines and also by canc elling the influence of CP on the proliferation of CTLL cells.)