Opioid peptides and immunodysfunction in patients with major depression and anxiety disorders.

To assess cell-mediated immunity in depression and anxiety disorders and to elucidate whether immunodysfunction might be related to a high opioid activity, a prospective study of patients with major depression (n = 34) or anxiety disorders (n = 21) was performed. Cellular immunity tests, the in vitro effects of naloxone on monocytes, and beta-endorphin plasma levels were investigated. Peripheral blood mononuclear cells and some monocyte parameters were determined by flow cytometry. Natural killer (NK) cell activity was studied by cytotoxicity, gamma-interferon production by a standard bioassay, monocytic phagocytosis by ingestion of Candida albicans and latex, and blastogenesis by stimulation with phytohaemaglutinin. In major depression and anxiety: 1) a marked reduction in the number of monocytes that ingested particles and expressed cytoskeletal intermediate filaments and surface structures (CR1 receptors and HLA-DR antigens); 2) a monocytosis that was not able to normalize the count of functioning monocytes; 3) an in vitro correction of the monocyte dysfunction by naloxone; 4) a decrease in NK cell number and activity; and 6) an anergy to candidin and tuberculin and a diminished lectin-induced blastogenesis were observed. Some of these immune changes correlated closely with plasma beta-endorphin abnormally high in all the cases. In conclusion, a naloxone-reversible monocyte dysfunction, associated to decreased NK activity and cell-mediated hypersensitivity, was found together with high of beta-endorphin plasma levels. In addition, results suggest that these immunological alterations may be useful in the clinical management of patients with these psychiatric diseases.