Influence of in Vivo Hydrocortisone on Some Human Blood Lymphocyte Subpopulations

Abstract

The effect of in vivo hydrocortisone (OHC) on natural killer (NK) activity was studied using the K562 cell line as target in a 3-h ⁵¹Cr-release assay. Peripheral blood lymphocytes obtained from live normal volunteers at 0, 4, 24 and 48 h after Intravenous administration of 300 mg of OHC showed significantly increased NK activity at 4 h, decreased activity at 24 h, with a return toward normal at 48 h. Parallel variation were found in the fraction of lymphocytes bearing receptor for the Fe part of IgG. However, neither the number of these cell nor the NK activity was influenced by the medication when the results were given per millilitre of blood. In vitro pre-incubation of the effector with OHC for 24 h had no effect on viability, expression of surface markers, or NK activity. It is concluded that under the present conditions NK activity is OHC-resistant. The variations observed after in vivo administration seem to be due to a reversible redistribution mainly affecting cells other than the NK effectors.