Influence of low doses of methotrexate on superoxide anion production by polymorphonuclear leukocytes from patients with rheumatoid arthritis.
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.
Laurindo
I M
IM
Department of Internal Medicine, Faculdade de Medicina da Universidade de São Paulo, Brazil.
Mello
S B
SB
Cossermelli
W
W
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*
D000838:Anions; D013481:Superoxides; D008727:Methotrexate