Some structural requirements for the prevention of leukopenia induced by nitrogen mustard.

Administration of L-cysteine hydrochloride to animals prior to the injection of nitrogen mustard (HN2) modifies the severe leukopenia characteristically induced by HN2 (1). However, if the L-cysteine hydrochloride is administered after HN2, even immediately, the leukopenia is not modified. It has not been demonstrated whether the effect of L-cysteine depends upon the presence of certain groups or groupings in the molecule or whether it is the result of non-specific chemical inactivation of HN2. Accordingly, the specificity as well as the mechanism of L-cysteine protection was investigated by correlating the chemical structure of related compounds with their ability to prevent HN2-induced leukopenia.