The C-terminal tetrapeptide of beta-endorphin (MPF) enhances lymphocyte proliferative responses.
Human MPF (Lys-Lys-Gly-Glu) stimulates the proliferative response of human lymphocytes to the T-cell mitogen concanavalin A by 121-751% in the concentration range 10(-11)-10(-4) M; the peak effect is at 10(-8) M, lower or higher concentrations eliciting reduced responses, i.e. the dose-response curve is bell-shaped. Species specificity is high. Human MPF similarly stimulates rat lymphocytes, but the peak effect is seen at a 100-fold higher dose (10(-6) M). Rat MPF (Lys-Lys-Gly-Gln) has a peak effect at 10(-6) M with human lymphocytes, but the peak effect with rat lymphocytes is at a 1000-fold lower dose (10(-9) M). Truncated forms of the MPFs (Gly-Glu, Gly-Gln, Gly, Glu, Gln) and opioid peptides (beta-endorphin, [Leu] and [Met]enkephalin) show insignificant or only weak stimulatory or inhibitory effects. These results suggest that MPF acts via specific non-opioid receptors located on lymphocytes and that endogenously released MPF may have an important role in the functioning of the immune system.
Owen
D L
DL
Department of Evolutionary and Environmental Biology, University of Liverpool, UK.
Morley
J S
JS
Ensor
D M
DM
Miles
J B
JB
D000818:Animals; D002455:Cell Division / Q000187:drug effects / Q000276:immunology; D003208:Concanavalin A / Q000494:pharmacology; D004151:Dipeptides / Q000494:pharmacology; D004306:Dose-Response Relationship, Immunologic; D004723:Endorphins / Q000494:pharmacology*; D004743:Enkephalin, Leucine / Q000494:pharmacology; D004744:Enkephalin, Methionine / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D005998:Glycine / Q000494:pharmacology; D006801:Humans; D008213:Lymphocyte Activation / Q000187:drug effects*; D008934:Mitogens / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D013045:Species Specificity; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D001615:beta-Endorphin / Q000494:pharmacology
D004151:Dipeptides; D004723:Endorphins; D008934:Mitogens; D009842:Oligopeptides; D010446:Peptide Fragments; D003208:Concanavalin A; C039788:glycylglutamine; D018698:Glutamic Acid; D004744:Enkephalin, Methionine; D004743:Enkephalin, Leucine; D001615:beta-Endorphin; C050079:lysyl-lysyl-glycyl-glutamic acid; C046223:N-glycylglutamic acid; D005998:Glycine