[Monocytic dysfunction by opioid peptides in patients with major depression]. 
Patients with depression present immunodepression and it has been proposed that, in these patients, endogenous opioid peptides may be mediators between the dysfunction of the central nervous system and immune alterations.  The function and the surface markers of monocytes were studied in 15 patients with major unipolar depression and in 24 healthy controls by biological trials of phagocytosis of Candida albicans and latex particles and immunofluorescence with monoclonal antibodies.  Most of the patients studied (86%) presented monocytic dysfunction characterized by diminished phagocytic activity and a decrease in the expression of intermediate filaments of vimentin of the cytoskeleton and membrane molecules (CR1, receptor for the Fc fraction of the IgG and HLA DR antigens).  Incubation of the patients monocytes with naloxone led to the disappearance of monocytic alterations in most of the patients.  Patients with major unipolar depression present a high opioid tone which has consequences in the function of the immune system.