title: Bariatric surgery reverses natural killer (NK) cell activity and NK-related cytokine synthesis impairment induced by morbid obesity.
abstract: BACKGROUND
  Obesity is related to a higher rate of infections and some types of cancer. Here we analyzed the impact of obesity and weight loss induced by Roux-en-Y gastric bypass (RYGB) on immunological parameters, i.e., cytokine productions and natural killer cell function.
  
  
  METHODS
  We analyzed 28 morbidly obese patients before and 6 months after RYGB. Biochemical parameters were analyzed in plasma. The percent of natural killer (NK) cells, their cytotoxicity, and the production of cytokines by peripheral blood mononuclear cells were analyzed. The percent of NK cells was determined by flow cytometry and cytokine production determined by enzyme-linked immunosorbent assay. NK cytotoxicity was determined by the lactate dehydrogenase release assay.
  
  
  RESULTS
  The weight loss 6 months following surgery was 35.3 ± 4.5 kg. RYGB also improves biochemical parameters. No significant difference was found in the percent of NK cells after surgery. We found an increase in the production of interferon-γ, interleukin (IL)-12 and IL-18, but not in IL-2, 6 months after RYGB. Cytotoxic activity of NK cells was significantly enhanced 6 months after RYGB [17.1 ± 14.7% before RYGB vs 51.8 ± 11.3% at 6 months after, at 40:1 effector to target cell ratio; p < 0.001]. We observed significant post-surgical improvement in the cytotoxic activity curve in 22 out of 28 patients (78.6%), irrespective of the target to effector cell ratio.
  
  
  CONCLUSIONS
  The weight loss induced by RYGB modifies the production of cytokines related with NK cell function and improves its activity.
authors.affiliation: Obesity and Metabolic Syndrome Group, Endocrinology Department, University of São Paulo Medical School General Hospital, São Paulo, Brazil.
authors.forename: Cristiane Martins
authors.initials: CM
authors.lastname: Moulin
authors.forename: Ivo
authors.initials: I
authors.lastname: Marguti
authors.forename: Jean Pierre Schatzmann
authors.initials: JP
authors.lastname: Peron
authors.forename: Alfredo
authors.initials: A
authors.lastname: Halpern
authors.forename: Luiz Vicente
authors.initials: LV
authors.lastname: Rizzo
mesh_terms: D000328:Adult; D016207:Cytokines / Q000096:biosynthesis* / Q000276:immunology; D005260:Female; D015390:Gastric Bypass; D006801:Humans; D007694:Killer Cells, Natural / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D009767:Obesity, Morbid / Q000276:immunology* / Q000601:surgery*; D015431:Weight Loss / Q000276:immunology
chemical_list: D016207:Cytokines
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