title: Immunostimulating effect of the synthetic peptide octarphin corresponding to β-endorphin fragment 12-19.
abstract: We have synthesized the peptide TPLVTLFK corresponding to β-endorphin fragment 12-19 (dubbed octarphin) and its analogs (LPLVTLFK, TLLVTLFK, TPLVLLFK, TPLVTLLK, TPLVTLFL). The octarphin peptide was labeled with tritium (specific activity 28 Ci/mol), and its binding to murine peritoneal macrophages was studied. [3H]Octarphin was found to bind to macrophages with high affinity (K(d) = 2.3 ± 0.2 nM) and specificity. The specific binding of [3H]octarphin was inhibited by unlabeled b-endorphin and the selective agonist of nonopioid b-endorphin receptor synthetic peptide immunorphin (SLTCLVKGFY) (K(i) = 2.7 ± 0.2 and 2.4 ± 0.2 nM, respectively) and was not inhibited by unlabeled naloxone, a-endorphin, γ-endorphin, or [Met(5)]enkephalin (K(i) > 10 mM). Inhibitory activity of unlabeled octarphin analogs was more than 100 times lower than that of unlabeled octarphin. Octarphin was shown to stimulate activity of murine immunocompetent cells in vitro and in vivo: at concentration of 1-10 nM it enhanced the adhesion and spreading of peritoneal macrophages as well as their ability to digest bacteria of Salmonella typhimurium virulent strain 415 in vitro; the peptide administered intraperitoneally at a dose of 20 µg/animal on day 7, 3, and 1 prior to isolation of cells increased activity of peritoneal macrophages as well as spleen T- and B-lymphocytes.
authors.affiliation: Branch of Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Pushchino, Moscow Region.
authors.forename: Yu A
authors.initials: YA
authors.lastname: Kovalitskaya
authors.forename: Yu N
authors.initials: YN
authors.lastname: Nekrasova
authors.forename: V B
authors.initials: VB
authors.lastname: Sadovnikov
authors.forename: Yu A
authors.initials: YA
authors.lastname: Zolotarev
authors.forename: E V
authors.initials: EV
authors.lastname: Navolotskaya
mesh_terms: D000276:Adjuvants, Immunologic / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D000595:Amino Acid Sequence; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D002478:Cells, Cultured; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology* / Q000494:pharmacology*; D010587:Phagocytosis / Q000187:drug effects; D012480:Salmonella Infections / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology; D012486:Salmonella typhimurium / Q000187:drug effects / Q000502:physiology; D001615:beta-Endorphin / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000276:Adjuvants, Immunologic; D009842:Oligopeptides; C555005:octarphin; D001615:beta-Endorphin