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.
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.
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.
MTX treatment may interfere with neutrophil superoxide production.