In vitro effects of single alkylating agents on normal peripheral blood lymphocytes

The separate in vitro effects of HN2 and L-PAM on resting and stimulated peripheral blood lymphocytes were evaluated with biochemical and morphologic experimental endpoints. Both alkylating agents caused dose-dependent reduction of protein, RNA, and DNA synthesis, but the patterns of diminution differed. The number of cells staining with Erythrosin B, as a toxicity indicator, also rose with higher drug concentrations, but a large proportion of lymphocytes remained unstained even at the maximum drug dose. Stimulation with PHA partially nullified the suppression caused by HN2 but did not influence the effects of L-PAM. Exposure to PWM rendered the in vitro HN2 innocuous but L-PAM remained cytotoxic. Simultaneous lectin-induced blastogenesis proceeded unaltered. Finally, comparisons between 72 and 4 hr drug exposures imply that interference with intracellular synthesis occurs promptly, continues after drug removal, and is related quantitatively to drug concentration rather than to duration of contact.