title: Influence of low doses of methotrexate on superoxide anion production by polymorphonuclear leukocytes from patients with rheumatoid arthritis.
abstract: OBJECTIVE
  The mechanism of methotrexate (MTX) action in rheumatoid arthritis (RA) is unclear. We assessed the influence of MTX on neutrophil superoxide production evaluated by ferricytochrome c reduction.
  
  
  METHODS
  Neutrophils were collected from MTX treated patients with RA (MTX-RA), patients with RA without medication (RA) and healthy donors, cocultured with MTX or MTX-RA serum.
  
  
  RESULTS
  Polymorphonuclear leukocytes (PMN) from MTX-RA showed decreased superoxide production when compared with cells collected from patients with RA and controls. Control PMN superoxide production was inhibited (36%) by MTX-RA serum incubation. This reduction was accompanied by clinical improvement. MTX had no activity in the in vitro assays.
  
  
  CONCLUSIONS
  MTX treatment may interfere with neutrophil superoxide production.
authors.affiliation: Department of Internal Medicine, Faculdade de Medicina da Universidade de São Paulo, Brazil.
authors.forename: I M
authors.initials: IM
authors.lastname: Laurindo
authors.forename: S B
authors.initials: SB
authors.lastname: Mello
authors.forename: W
authors.initials: W
authors.lastname: Cossermelli
mesh_terms: D000328:Adult; D000368:Aged; D000838:Anions / Q000378:metabolism; D001172:Arthritis, Rheumatoid / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D001790:Blood Physiological Phenomena; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D008297:Male; D008727:Methotrexate / Q000494:pharmacology*; D008875:Middle Aged; D009504:Neutrophils / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*
chemical_list: D000838:Anions; D013481:Superoxides; D008727:Methotrexate