Cysteine esters protect cultured rodent lung slices from sulphur mustard.

1. In previous studies an in vitro rat lung slice system was used to investigate the metabolic and structural changes after exposure to known lung toxicants. 2. In this study, the same system was used to identify the ability of cysteine esters to protect against sulphur mustard toxicity. 3. The cyclopentyl (CCPE), cyclohexyl (CCHE), isopropyl (CIPE), methyl (CME) esters of cysteine, cystine dimethyl ester (CDME), cysteine (CySH) and N-acetyl cysteine (NAc) were all non-toxic to cultured rat lung slices at 5 mM (equivalent cysteine concentration) after a pretreatment time of 30 min. 4. Pretreatment with the isopropyl, cyclohexyl, cyclopentyl and methyl esters of cysteine at concentrations higher than 1 mM protected against an IC50 of sulphur mustard, however, neither cysteine nor N-acetylcysteine protected. 5. We propose that the extent of protection is directly related to increased levels of intracellular cysteine provided by the esters of cysteine.