The effect of sulphasalazine on neutrophil superoxide generation in rheumatoid arthritis

The production of superoxide by the peripheral blood neutrophils of 19patients with active rheumatoid arthritis was measured during treatmentwith sulphasalazine (SASP). The response to drug treatment was determinedby change in plasma viscosity, CRP, early morning stiffness and articularindex over a 10-point scale. Of the 19 patients studied, eight wereconsidered to have responded well to SASP and seven to have respondedpoorly or not at all. Over the treatment period, plateau levels ofsuperoxide production fell in seven of the eight responders (P = 0.028)compared with a non-significant fall in 3/7 of the non- responder groups.The initial rate of superoxide production also fell in the responder group,but this was not statistically significant. Initial values in both theresponder and non-responder groups were comparable with those seen fornormal controls. Analysis of drug levels showed all patients to becompliant with drug treatment; however, drug levels and neutrophil activitywere not correlated. Studies of the effect of SASP and sulphapyridine onsuperoxide production in vitro showed no difference between good and poorresponders. These results suggest that there is no inherent differencebetween good and poor responders regarding the susceptibility of theirneutrophils to SASP. SASP's action on neutrophils, therefore, appears notto be its main mechanism of disease-modifying activity in RA.