The Differential Effect of In Vivo Hydrocortisone on the Kinetics of Subpopulations of Human Peripheral Blood Thymus-Derived Lymphocytes

The present study was undertaken to determine the effect of in vivo hydrocortisone on the kinetics of subpopulations of normal human peripheral blood (PB) thymus-derived (T) cells. Normal volunteers received a single i.v. dose of hydrocortisone, and blood was taken just before, as well as 4, 24, and 48 h after hydrocortisone administration. T cells were purified from each specimen, and proportions and absolute numbers of T lymphocytes bearing receptors for the Fc portion of IgG (T_·G) and for the Fc portion of IgM (T_·M) were enumerated by rosetting T cells with bovine erythrocytes which had been coated with either antibovine erythrocyte IgG or IgM. 4 h after i.v. administration of hydrocortisone, T_·M cells decreased from 52 (±5%) to 23 (±6%) of PB T cells (P < 0.01) and the absolute number of T_·M cells decreased from 1,028 (±171) per mm³ to 103 (±23) per mm³ (P < 0.001). In contrast, relative proportion of T_·G cells increased from 22 (±4%) to 66 (±7%), while the absolute numbers of T_·G cells were essentially unchanged (P > 0.2). In vitro studies involving preincubation of T cells with hydrocortisone before rosette determination of T_·G or T_·M cells demonstrated that the decrease in absolute numbers of T_·M cells did not represent hydrocortisone interference with T_·M rosette formation, nor did it represent a switch of T_·M cells to T_·G cells. Thus, administration of hydrocortisone to normal subjects produces a selective depletion from the circulation of T lymphocytes which possess receptors for the Fc portion of IgM (T_·M cells) and of T cells which possess no detectable F_C receptor (T_{·non−M, non−G} cells). T_·G cells are relatively resistant to the lymphopenic effect of hydrocortisone. These data clearly demonstrate that in vivo corticosteroids have a differential effect on the kinetics of identifiable and distinct subsets of cells in the human T-cell class.

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