Age-related changes in mitogen-induced beta-endorphin release from human peripheral blood mononuclear cells

beta-Endorphin is an opioid peptide synthesized in the pituitary, hypothalamus, and immunocytes, known to affect immune responses both when added in vitro and when its synthesis is increased in vivo (e.g., during stress). We show here that, similar to its concentrations in peripheral blood mononuclear cells, the release of the opioid peptide from these cells after stimulation with polyclonal mitogens such as PHA or Con-A is also age dependent. Moreover, the effect of both mitogens on Ca2+ homeostasis changes with age. Finally, the ionophore ionomycin and the Ca2+ ATPase blocker thapsigargin induce the same age related effect on beta-endorphin release. For these reasons, we suggest that calcium homeostasis might be important for the differences observed in the release of the opioid from cells obtained from younger (< or = 30 years) or older (> or = 45 years) volunteers.