title: [Morphine inhibits complement receptor expression, phagocytosis and oxidative burst by a nitric oxide dependent mechanism].
abstract: OBJECTIVE
  Monocytes play a crucial role in the immune response by recognition, ingestion, and intracellular killing of microorganisms. We investigated whether morphine and fentanyl influence CD 11b and CD35 surface receptor expression, phagocytic activity and superoxide anion generation of monocytes in a whole blood flow cytometric assay.
  
  
  METHODS
  Whole blood of 13 healthy volunteers was incubated with different morphine and fentanyl concentrations. Expression of surface receptors CD 11b and CD35 was determined by fluorochrome-labelled antibodies. Phagocytic activity was assessed by ingestion of fluorescent bacteria. Conversion of dihydrorhodamin served for oxidative burst measurements.
  
  
  RESULTS
  Morphine inhibited monocyte function in a concentration and time dependent manner. Morphine-induced changes were abolished by preincubation with the NO synthase inhibitor N-nitro-l-arginine as well as naloxone. Fentanyl failed to inhibit receptor expression, phagocytosis and reactive oxygen production by monocytes in clinically relevant as well as supraclinical concentrations.
  
  
  CONCLUSIONS
  Our results suggest that these monocyte functions are inhibited by a morphine-stimulated NO release mediated by a mu opiate receptor subtype expressed on the surface of monocytes. In contrast, fentanyl did not share morphine's inhibitory effects on monocyte activity.
authors.affiliation: Abteilung Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Giessen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Menzebach
authors.forename: J
authors.initials: J
authors.lastname: Hirsch
authors.forename: R
authors.initials: R
authors.lastname: Nöst
authors.forename: M
authors.initials: M
authors.lastname: Mogk
authors.forename: G
authors.initials: G
authors.lastname: Hempelmann
authors.forename: I D
authors.initials: ID
authors.lastname: Welters
mesh_terms: D000328:Adult; D039481:CD11b Antigen / Q000097:blood / Q000187:drug effects / Q000235:genetics*; D005283:Fentanyl / Q000494:pharmacology*; D006801:Humans; D008297:Male; D009000:Monocytes / Q000187:drug effects / Q000276:immunology; D009020:Morphine / Q000494:pharmacology*; D009569:Nitric Oxide / Q000502:physiology*; D010587:Phagocytosis / Q000187:drug effects*; D011951:Receptors, Complement / Q000037:antagonists & inhibitors*; D017463:Receptors, Complement 3b / Q000097:blood / Q000187:drug effects / Q000235:genetics*; D012016:Reference Values; D016897:Respiratory Burst / Q000187:drug effects*
chemical_list: D039481:CD11b Antigen; D011951:Receptors, Complement; D017463:Receptors, Complement 3b; D009569:Nitric Oxide; D009020:Morphine; D005283:Fentanyl