Hypothalamic-pituitary-adrenal axis function, psychopathological traits, and natural killer (NK) cell activity in...

To evaluate the role of Hypothalamic-Pituitary-Adrenal (HPA) hormones and psychoneuroendocrine modulation on NK cell activity in Anorexia Nervosa (AN) we studied in 24 patients and 20 sex- and age-matched healthy controls, the spontaneous NK activity of peripheral blood mononuclear (PBM) cells and the susceptibility in vitro to cortisol or immune interferon or interleukin-2. NK cytotoxicity of PBM cells was measured in a direct non-radiometric 4h cytolytic assay using K562 cells as targets. HPA axis function was evaluated by IV ovine Corticotropin Releasing Hormone (o-CRH) administration. We did not find clear-cut abnormalities of NK cytotoxicities either in basal conditions or after exposure to challengers. The extent of cortisol-dependent inhibition was comparable in patients and controls. Significant inverse and direct correlations were found respectively between the spontaneous NK cell activity and baseline serum cortisol at 0800 h (r = -0.5; p < .02), and between IL-2 dependent boosting of NK cell cytotoxicity and ACTH, beta-endorphin or cortisol responses after o-CRH, expressed as areas under the curve (AUC) (r = 0.46, p < .05; r = 0.46, p < .05; and r = -0.48, p < .05, respectively). Correlations observed with AUC ratios yielded more significant results (r = 0.62; p < .01 and r = 0.51; p < .05 respectively). These data suggest a role for Proopiomelanocortin (POMC) derived peptides in the regulation of NK cell activity in AN, and multifaceted relationships between this particular immune function, on the one hand, and certain patterns of HPA axis function on the other.