IMMUNOMODULATING EFFECT OF MET-ENKEPHALIN ON DIFFERENT STAGES OF LYMPHOCYTE-PROLIFERATION INDUCED WITH CONCANAVALIN-A IN-VITRO

Met-enkephalin (ME) in the range of concentrations 10(-15) M to 10(-9) M has exhibited an immunomodulating effect on concanavalin A (Con A) induced proliferation of mice Lymphocytes from lymph nodes in vitro. T he effect of ME was shown to vary with the stage of lymphocyte activat ion and to depend on the mitogen dose. In the case that ME and Con A w ere injected simultaneously, at the zero time of proliferation, maximu m inhibition was observed on the first and fourth days. In an other se t of experiments when ME was added at intervals of 4 hours before meas uring the proliferation response value, both inhibition (after 24 hour s of proliferation) and stimulation (after 28 and 96 hours) were obser ved. Opioid ligands of various classes were found to act in the same m anner as ME. Naloxone was shown to block the immunomodulating effect o f opioids.