Effect of corticosteroid therapy on blood monocyte superoxide generation in rheumatoid arthritis: studies in vitro and ex vivo.

Rates of superoxide (SA) generation by blood monocytes stimulated ex vivo were studied before and during corticosteroid treatment of rheumatoid arthritis (RA) patients, in control patients and in healthy controls. The direct effect on stimulated SA production of pre-incubating cells with prednisolone in vitro was also studied. Significant inhibition of monocyte SA output stimulated with IgG-treated zymosan (ITZ) and fluoride ion (F), but not serum-treated zymosan (STZ) was demonstrated following steroid therapy in RA. No inhibitory effect of prednisolone could be demonstrated in vitro, using ITZ, STZ and F as stimuli. Our data on blood monocyte yields, size and cytochemistry suggest that the in vivo effect is due to a shift in blood monocyte traffic.