Immune regulation in Cushing's syndrome: relationship to hypothalamic-pituitary-adrenal axis hormones

Hormones of the hypothalamic-pituitary-adrenal (HPA) axis are connected closely with immune measures. To investigate whether Cushing's syndrome (CS) is associated with immune dysregulation, we compared the percentage of specific lymphocyte subsets as well as natural cell activity (NKCA) in 48 patients with Cushing's syndrome and 48 age- and sex-matched normal controls. Lymphocyte subset analysis included the percentage of lymphocytes expressing CD3 (total T), CD4 (T helper/inducer), CD8 (T suppressor/cytotoxic) and CD56 (NK cell) antigens. Baseline plasma concentrations of cortisol, ACTH and beta-endorphin as well as 24 h urinary-free cortisol (UFC) levels also were determined. Results indicated a decrease in the percentage of CD4+ cells (p < 0.05), an increase in percentage of CD8+ cells (p < 0.05), a decrease in CD4/CD8 ratios (p < 0.01), and a reduction in NKCA (p < 0.05) in patients with CS compared to matched controls. We also found significant negative correlations between NKCA on the one hand and 24 h UFC (p < 0.05) and plasma beta-endorphin (p < 0.05) on the other. These results indicate there is immune dysregulation in CS patients which can be explained in part by an increase in HPA-axis hormones.