The immunomodulatory action of frentizole, a novel immunosuppressive agent

The in vitro effects of frentizole and methylprednisolone on human PBL were examined. Both drugs exhibited differential effects on lymphocyte subpopulations. Frentizole was more effective in suppressing human lymphocytes responding to Con A and PWM, than it was in cells activated by PHA, specific antigen, or alloantigen. Methylprednisolone, on the other hand, was more inhibitory for cells stimulated by PHA, specific antigen, or alloantigen. These data suggest that frentizole has a preferential effect on the cytotoxic/suppressor subpopulation of human T lymphocytes while methylprednisolone appears to preferentially affect the helper/inducer subset. Differences in potency between the two drugs were also observed. Methylprednisolone was better able to maintain its inhibitory effects during longer periods of culture than frentizole. Both agents were less effective if their addition to the culture was delayed 24-48 hrs and neither drug was very effective in overcoming the adjuvant action of poly A:U on mitogenically activated human PBL.