A further exploration of the relationships between immune parameters and the HPA-axis activity in depressed patients

In order to investigate the relationship between the immune apparatus and the hypothalamic-pituitary-adrenal (HPA)-axis activity in depressed patients, we measured in vitro lymphocyte responses to the mitogens Phytohaemagglutinin (PHA), Pokeweed (PWM) and Concanavalin A (Con A) and 8 a.m. baseline cortisol values in plasma, free cortisol excretion in 24 h urine (UFC), basal and post-dexamethasone beta-endorphin values. Major depressed patients with melancholia/psychotic features exhibited a significantly lower mitogen-induced blast transformation as compared to minor and simple major depressed patients. The lymphocyte responses to the three mitogens were significantly inversely related to baseline cortisol values and postdexamethasone beta-endorphin values. The proliferative capacity of lymphocytes to stimulation with PHA and PWM was significantly and positively related to UFC excretion. Up to 45% of the variance in the immune-responses to the mitogens was explained by the baseline cortisol, post-dexamethasone beta-endorphin and UFC values.