Assessment of peripheral blood CD4+ adenosine triphosphate activity in patients with rheumatoid arthritis

Objective The ability of the ImmuKnow (Cylex) assay to predict the risk of infection in rheumatoid arthritis (RA) patients receiving synthetic or biological disease-modifying antirheumatic drugs (DMARDs) was examined. Methods The amount of adenosine triphosphate (ATP) produced by CD4+ cells in response to phytohemagglutinin was measured in whole blood from 117 RA patients without infection versus 17 RA patients with infection, and compared with results in 75 healthy controls. Results The mean ATP level was significantly lower in patients with infection compared to both healthy controls ( P < 0.0005) and patients without infection ( P = 0.040). Also, the mean ATP level in patients without infection was significantly lower than that in healthy controls ( P = 0.012). There was no correlation between the ATP level and the Disease Activity Score in 28 joints. Conclusion ImmuKnow assay results may be effective in identifying RA patients at increased risk of infection, but the results showed no correlation with RA activity. Larger studies are required to establish the clinical advantages of this assay in RA treatment.