beta-endorphin and Cell-Transformation--Neoplastic

Beta-endorphin and the synthetic beta-endorphin-like decapeptide Ser-Leu-Thr-Cys-Leu-Val-Lys-Gly-Phe-Tyr (referred to as immunorphin), corresponding to the sequence 364-373 of the CH3 domain of human immunoglobulin G heavy chain, were shown to stimulate concanavalin A-induced proliferation of T lymphocytes from the blood of healthy donors. [Met(5)]Enkephalin and the antagonist of opioid receptors naloxone examined in parallel were inactive. The stimulating effect of beta-endorphin and immunorphin on T lymphocyte proliferation is not inhibited by naloxone. Studies on receptor binding of (125)I-labeled immunorphin to T lymphocytes revealed that it binds with high affinity to naloxone-insensitive receptors (K(d) = 7.0 +/- 0.3 nM). Unlabeled immunorphin completely inhibits (125)I-labeled beta-endorphin specific binding to naloxone-insensitive receptors on T lymphocytes (K(i) = 0.6 +/- 0.1 nM). Thus, beta-endorphin and immunorphin interact with common naloxone-insensitive receptors on T lymphocytes.

Topics: beta-Endorphin; Binding, Competitive; Cell Division; Cell Transformation, Neoplastic; Concanavalin A; Enkephalin, Methionine; Humans; Immunoglobulin Constant Regions; Immunoglobulin G; Immunoglobulin gamma-Chains; Immunoglobulin Heavy Chains; Iodine Radioisotopes; Lymphocyte Activation; Naloxone; Narcotic Antagonists; Oligopeptides; Peptide Fragments; Receptors, Opioid; T-Lymphocytes