Endogenous opioid peptides and the immune system

: Several studies have demonstrated that endogenous opioid peptides produced by the neuroendocrine system can modulate several immunological functions. Immune system cells have also been shown to have the ability to synthesize and release such peptides. This would mean that the neuroendocrine and immunological systems share molecules and opioid receptors and it may be that peptides produced by the neuroendocrine system modify immunocompetence and that these same substances released by macrophages that infiltrate inflamed tissue also act on the pain response in the zone of lesions. We aimed to investigate the immunoregulatory function of endogenous opioid peptides and their effects on the complement system's natural "killer" cell activity, chemotaxis, phagocytosis and oat cell activity.