The immunosuppressive potency of various steroids on peripheral blood lymphocytes, T cells, NK and K cells

The immunosuppressive effect of natural and synthetic steroids was tested in vitro on phytohemagglutinin (PHA) stimulated T lymphocytes and peripheral blood lymphocytes (PBL), as well as on NK and K cell activity. Three groups of steroids, significantly different in their immunosuppressive activity, were identified. Fluorohydrocortisone, and methylprednisolone were highly potent in suppressing PHA stimulation of T lymphocytes and PBL. Hydrocortisone was of intermediate potency, whereas cortisone, dihydrocortisol, and tetrahydrocortisol were of low potency. T lymphocytes were more sensitive to the suppressive effect of fluorohydrocortisone and methylprednisolone than were PBL cultures. NK and K cell activity was suppressed only by the high potency synthetic steroids and even then the suppression of K cell activity was not significant except at high in vitro steroid concentrations. The present findings support the conception that different lymphocyte subpopulations have different susceptibility to the effect of highly potent steroids. Thus, lymphocyte heterogeneity must be taken into account when the immunosuppressive potencies of different glucocorticoids are studied. Furthermore, the findings in different lymphocyte populations ranked the relative in vitro immunosuppressive potency of glucocorticoids different from the relative anti-inflammatory potencies reported in the literature.