title: Depletion and recovery of lymphoid subsets following morphine administration.
abstract: OBJECTIVE
  Opioid use and abuse has been linked to significant immunosuppression, which has been attributed, in part, to drug-induced depletion of lymphocytes. We sought to define the mechanisms by which lymphocyte populations are depleted and recover following morphine treatment in mice.
  
  
  METHODS
  Mice were implanted with morphine pellets and B- and T-cell subsets in the bone marrow, thymus, spleen and lymph nodes were analysed at various time points. We also examined the effects of morphine on T-cell development using an ex vivo assay.
  
  
  RESULTS
  The lymphocyte populations most susceptible to morphine-induced depletion were the precursor cells undergoing selection. As the lymphocytes recovered, more lymphocyte precursors proliferated than in control mice. In addition, peripheral T-cells displayed evidence that they had undergone homeostatic proliferation during the recovery phase of the experiments.
  
  
  CONCLUSIONS
  The recovery of lymphocytes following morphine-induced depletion occurred in the presence of morphine and via increased proliferation of lymphoid precursors and homeostatic proliferation of T-cells.
authors.affiliation: Department of Microbiology, Molecular Genetics, and Immunology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: E Y
authors.initials: EY
authors.lastname: Zhang
authors.forename: J
authors.initials: J
authors.lastname: Xiong
authors.forename: B L
authors.initials: BL
authors.lastname: Parker
authors.forename: A Y
authors.initials: AY
authors.lastname: Chen
authors.forename: P E
authors.initials: PE
authors.lastname: Fields
authors.forename: X
authors.initials: X
authors.lastname: Ma
authors.forename: J
authors.initials: J
authors.lastname: Qiu
authors.forename: T M
authors.initials: TM
authors.lastname: Yankee
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001402:B-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D001853:Bone Marrow / Q000187:drug effects / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000276:immunology; D003345:Corticosterone / Q000097:blood; D008198:Lymph Nodes / Q000187:drug effects / Q000276:immunology; D018655:Lymphocyte Count; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009020:Morphine / Q000494:pharmacology*; D009294:Narcotics / Q000494:pharmacology*; D013154:Spleen / Q000187:drug effects / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects* / Q000276:immunology; D013950:Thymus Gland / Q000187:drug effects / Q000276:immunology
chemical_list: D000701:Analgesics, Opioid; D009294:Narcotics; D009020:Morphine; D003345:Corticosterone