Monocytes and granulocytes in rheumatoid arthritis (RA): phagocytic activity and superoxide anion production

Nonsteroidal antiinflammatory drugs interact with horseradish peroxidase in an in vitro assay system for hydrogen peroxide scavenging

The established horseradish peroxidase/guaiacol in an in vitro assay system was used for investigation of the reactivity of nonsteroidal antiinflammatory drugs with hydrogen peroxide. Although the drugs rapidly seemed to react in the selected conditions, difficulties were encountered in attempts to quantify the reaction and an interaction with horseradish peroxidase was suspected. A more specific assay system based on the absolute specificity of the enzyme glutathione peroxidase for glutathione was subsequently used which demonstrated that none of the investigated nonsteroidal antiinflammatory drugs was able to scavenge hydrogen peroxide. An original procedure to further evidence the interaction was developed thereafter, based on the reaction of 5-aminosalicylic acid with similar hemoproteins. This led to the demonstration that nonsteroidal antiinflammatory drugs were substrates for horseradish peroxidase and explained their reactivity in the horseradish peroxidase/guaiacol assay system. The compound 5-aminosalicylic acid showed an unusual behaviour that was attributed to its ability to both scavenge hydrogen peroxide and interact with horseradish peroxidase. It was concluded that the lack of specificity of horseradish peroxidase for its donor substrate may lead to erroneous results in assays for hydrogen peroxide scavenging of some drugs. An alternative method is however available and a simple spectroscopic assay can evidence the interaction with horseradish peroxidase.

Effects of methotrexate, sulphasalazine and aurothiomalate on polymorphonuclear leucocytes in rheumatoid arthritis

The aim of the study was to evaluate the effects of treatment with methotrexate, sulphasalazine and aurothiomalate on polymorphonuclear leucocytes (PMN) in rheumatoid arthritis (RA). Circulating PMNs from 58 RA patients treated with either methotrexate (n = 27), sulphasalazine (n = 16) or aurothiomalate (n = 15) were assayed for their chemotactic capacity and generation of superoxide anions. The expression of CD18/CD11b was measured for 17 RA patients treated with methotrexate. Chemotaxis and generation of superoxide anions were not affected by any of the three drugs. We found no difference in the expression of CD18/CD11b in RA patients treated with methotrexate compared to healthy subjects. Further methotrexate and aurothiomalate did not in vitro alter chemotaxis, generation of superoxide anion or expression of CD18/CD11b on normal PMNs. In conclusion we found no evidence that the effect of methotrexate, aurothiomalate or sulphasalazine in RA can be explained by modulation of chemotactic ability or superoxide anion generation of peripheral circulating PMNs.

Disseminated pustular dermatosis in polycythemia vera. Relationship with neutrophilic dermatosis of myeloproliferative disorders: study of neutrophil function

An unusual case of disseminated pustular eruption associated with polycythemia vera is described. This eruption can be included in the group of neutrophilic dermatoses of myeloproliferative disorders (pyoderma gangrenosum, Sweet's syndrome). A defect in superoxide anion (O2-) generation is detected. The fact that both the clinical condition and the neutrophil function improved with the use of dapsone suggests that the O2- generation defect may play a role in the pathogenesis of the eruption. From an evolutionary standpoint, the occurrence of a neutrophilic dermatosis in polycythemia vera could be an unfavorable sign of preleukemia.