title: Methionine-enkephalin stimulates in vitro proliferation of human peripheral lymphocytes via delta-opioid receptors.
abstract: The influence of methionine-enkephalin (Met-Enk) on in vitro proliferation of human peripheral lymphocytes was investigated. Met-Enk, in the concentration range 10(-12) to 10(-4) M enhanced the proliferative response to suboptimal concentrations of concanavalin A of human peripheral lymphocytes and to cells in the absence of mitogen. The response to Met-Enk in the absence of mitogen was not influenced by the presence of fetal calf serum: similar levels of enhancement were seen in cultures supplemented with 10% autologous serum. Enhancement of proliferation was blocked in a concentration-dependent manner by both naloxone and the delta specific antagonist ICI-174864. The sensitivity to the antagonistic influence of ICI-174864 suggests strongly that the stimulatory influence of Met-Enk on human lymphocyte proliferation in the absence of mitogen is mediated via the delta-opioid receptor.
authors.affiliation: Polytechnic of Central London, School of Paramedical Studies, England.
authors.forename: F H
authors.initials: FH
authors.lastname: Hucklebridge
authors.forename: B N
authors.initials: BN
authors.lastname: Hudspith
authors.forename: J
authors.initials: J
authors.lastname: Muhamed
authors.forename: P M
authors.initials: PM
authors.lastname: Lydyard
authors.forename: J
authors.initials: J
authors.lastname: Brostoff
mesh_terms: D000328:Adult; D000818:Animals; D001798:Blood Proteins / Q000494:pharmacology; D002417:Cattle; D002478:Cells, Cultured; D003208:Concanavalin A / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000494:pharmacology*; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000378:metabolism*; D008213:Lymphocyte Activation / Q000187:drug effects*; D008297:Male; D008875:Middle Aged; D009270:Naloxone / Q000494:pharmacology; D011957:Receptors, Opioid / Q000187:drug effects / Q000276:immunology*
chemical_list: D001798:Blood Proteins; D011957:Receptors, Opioid; D003208:Concanavalin A; D009270:Naloxone; D004744:Enkephalin, Methionine