PURINE ENZYMES IN RHEUMATOID-ARTHRITIS - POSSIBLE ASSOCIATION WITH RESPONSE TO AZATHIOPRINE - A PILOT-STUDY

Objective-To study the possible association of purine enzyme activitie s with response to azathioprine (AZA) treatment in rheumatoid arthriti s (RA) and their correlation with parameters of disease activity. Pati ents and methods-Lymphocyte activities of hypoxanthine-guanine phospho ribosyl-transferase (HGPRT), adenine phosphoribosyltransferase (APRT), purine nucleoside phosphorylase (PNP) and 5'-nucleotidase (5NT), and erythrocyte activities of thiopurine methyltransferase (TPMT) were mea sured in 14 healthy controls and 36 patients with RA. Eight patients h ad not previously been treated with AZA, Response to AZA therapy in 28 patients, determined in a prospective trial, was considered good in n ine (group 1), insufficient in seven (group 2). In 12 patients AZA was withdrawn because of adverse reactions (group 3). Disease activity pa rameters were obtained simultaneously with purine enzyme measurements. Purine enzyme levels in the different groups were compared. Results-L evels of 5NT activity were significantly lower in patients with RA tha n in healthy controls. PNP activity was higher in patients with RA not using prednisone compared with those who did and healthy controls. No clear correlation between purine enzyme levels and disease activity p arameters was found. 5NT activities were significantly higher in group one than in group three (p = 0.012; alpha = 0.017), and almost signif icantly higher than in group two (p = 0.03; alpha = 0.017). Conclusion s-The results indicate that purine enzyme activities in patients with RA differ from healthy controls, are associated with the outcome of AZ A treatment and seem not to be associated with disease activity. Our f indings may offer a clue to predict the response to AZA therapy in RA.