The subjects undergo a thorough medical (physical and blood/urine tests) and psychiatric evaluation to determine eligibility after signed informed consent is obtained. If eligible, the subject will complete questionnaires and undergo structured clinical interviews with a study psychiatrist. The subject will then undergo a 2-day testing period during which time, blood is drawn each morning at 8 am, with the subject taking 0.5 mg of dexamethasone (a synthetic steroid) at 11 pm prior to the second day of blood testing. About 80 ml of blood will be drawn on each morning. The blood collected will then be assayed for cortisol dexamethasone, lymphocyte glucocorticoid receptor levels; cytokine levels in plasma and lipopolysaccharide stimulated and unstimulated whole blood (IL-2, sIL-2R, IL-6, sIL-6R, and IL-10); lymphocyte subsets (T helper and suppressor, B, and Natural Killer cell numbers), and antigen stimulation responses to tetanus and candida. In addition, blood from the first day of testing will undergo ex vivo challenge with dexamethasone at varying concentrations to determine differential cytokine sensitivities to steroid exposure in subjects.
