Brain Peptide Reverses Effect of Morphine on Human Lymphocytes

E-rosette formation by human lymphocytes incubated with sheep red blood cells (sRBC) is inhibited by morphine. We studied the ability of the opiate antagonists naloxone and Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) to block this action. Active E-rosette formation by lymphocytes incubated with morphine was reduced from the control of 35.7±1.7% to 23.7±1.5% (p\u3c0.001). Similarly, total E-rosette formation was reduced by morphine from the control of 65.8±1.3% to 53.2±2.9% (p\u3c0.001). These effects were blocked by co-incubation of the lymphocytes with either Tyr-MIF-1 or naloxone (p\u3c0.05). Tyr-MIF-1 was active (p\u3c0.05) at concentrations as dilute as 10-13M. These results indicate that the neuropeptide Tyr-MIF-1 exerts an antiopiate effect at the human T-lymphocyte

In Vitro Studies of Tyr-MIF-1 With Human Lymphocytes

Our previous report showed that the brain peptide Tyr-MIF-1 (Tyr-Pro-Leu-Gly-NH2) blocks the inhibitory effect of morphine sulfate on E-rosette formation by human peripheral blood lymphocytes (PBL). In this study, additional in vitro effects of Tyr-MIF-1 on human PBL were studied. The percentages of positive cells for CD 2, a sheep erythrocyte receptor, CD 4 and CD 8 were unchanged after incubation of PBL with morphine or morphine plus Tyr-MIF-1. Tyr-MIF-1 was not mitogenic by itself. The addition of Tyr-MIF-1 did not increase the proliferative response of PBL to Con A, although morphine did. Tyr-MIF-1 did not activate PBL to produce IL 2 nor did it affect the production of IL 2 by Con A-stimulated PBL. The results suggest that Tyr-MIF-1 does not directly modulate CD 2, CD 4 and CD 8 expression, does not alter the proliferative response of PBL, and does not affect the production of IL 2

Failure of Met-Enkephalin to Enhance Natural Killer Cell Activity

Several papers have reported the enhancing effects of opiate peptides, like Met-enkephalin, on natural killer (NK) cell activity. We examined the actions of Met-enkephalin on NK activity in blood obtained from 18 different donors, of different ages, many of them on several occasions, at several ratios of effector to target cells, several concentrations of peptide, in several types of flasks, with the purity and identity of the pentapeptide verified by chromatography, in a system responsive to interferon, and with results calculated in different ways. No significant increase was found for the peptide for any ratio of cells, any concentration of peptide, or any single subject, even when the subjects with the lowest baseline NK cell activity were used or when the subjects were more than 60 years old. Instead of an increase, the combined results for all subjects at all ratios at all concentrations of Met-enkephalin showed an overall decrease of 31.3 % specific cytotoxicity. These results fail to support the reports of an enhancing effect of Met-enkephalin on NK cell activity