Effect of morphine on Fc-mediated phagocytosis by murine macrophages in vitro

J Neuroimmunol. 1997 Apr;74(1-2):111-6. doi: 10.1016/s0165-5728(96)00213-5.


Acute exposure to morphine has been shown to inhibit phagocytosis in murine macrophages, whereas chronic exposure results in apparent desensitization. We now show that morphine may be either inhibitory or stimulatory depending on concentration and exposure time. Furthermore, under some conditions drug withdrawal from putatively desensitized cells will result in inhibition of phagocytosis, suggesting that a state akin to dependence has developed. Desensitization can also develop with intermittent exposures if the opiate-free period between drug exposures is shorter than 4 h. These effects of morphine on macrophages are important in understanding the role of this drug as an immunomodulatory agent.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cells, Cultured
  • Drug Administration Schedule
  • Erythrocytes / physiology
  • Female
  • Macrophages, Peritoneal / drug effects*
  • Macrophages, Peritoneal / physiology*
  • Mice
  • Mice, Inbred C3H
  • Morphine / administration & dosage
  • Morphine / adverse effects
  • Morphine / pharmacology*
  • Narcotics / pharmacology*
  • Osmolar Concentration
  • Phagocytosis / drug effects*
  • Phagocytosis / physiology
  • Receptors, Fc / physiology*
  • Sheep / blood
  • Substance Withdrawal Syndrome / physiopathology
  • Time Factors


  • Narcotics
  • Receptors, Fc
  • Morphine