erum Cortisol Levels and Immune-Associated Antigens on the Surface of Peripheral Blood Lymphocytes after Dexamethasone Suppression Test in Healthy Young Men

Serum cortisol response to the 1-mg overnight Dexamethasone Suppression Test (DST) was studied in 19 healthy young men who were between 22 and 25 years old. Furthermore, we investigated changes in the ratio of lymphocyte subsets in peripheral blood sampled during DST, using two-color flowcytometry analysis. The types of lymphocytes according to the combination of surface antigens, were (1) T/B cell, (2) CD4/CD8, (3) HLA-DR/CD4 and (4) HLA-DR/CD8. Baseline concentrations of cortisol before DST were not high like those reported in depressive patients. After oral administration of dexamethasone cortisol levels severely decreased, suggesting that the Hypothalamic-Pituitary-Adrenal (HPA) axis responded sharply to dexamethasone in healthy young men. With respect to the ratio of lymphocyte subsets, CD8^+T-lymphocytes significantly increased after dexamethasone administration (p<0.05). The ratios of HLA-DR^+T-cells of other susets, did not change significantly after dexamethasone administration. These findings suggested that the immune systems of healthy young men was affected by dexamethasone directory or secondarily to an increase in the CD8^+T-lymphocyte subset.