Background JIA is the common chronic rheumatic disease in children that may continue to be active in adulthood. The new laboratory markers are needed to adjust therapy of JIA to the actual disease activity and to define group of patients with a risk of developing exacerbation. NPT (a product of guanosine triphosphate pathway) is produced by human monocytes/macrophages upon stimulation by Th1 derived INF-γ. Activated T cells release a soluble form of IL-2, considered to be en early marker for immune activation.

Objectives To assess whether serum levels of NPT and sIL-2R are reliable parameters for monitoring JIA activity in the clinical practice.

Methods 83 patients with active JIA (median 10.3y, 37 oligoarticular [OLIGO], 30 polyarticular [POLY], 6 systemic [soJIA], and 10 enthesitis-related–arthritis [ERA]onset) were evaluated. Of these, 38 consecutive patients were followed-up with an evaluation in remission.ACR-Pediatric variables: physician global assessment of disease activity; parent/patient assessment of overall well-being; CHAQ; number of joints with active arthritis; number of joints with limited range of motion; ESR/C-reactive protein; and additionally: duration of morning stiffness, WBC, and Hgb were collected. 25 ages- and sex- matched healthy subjects acted as controls. Serum levels of NPT and sIL-2R were measured by ELISA.

Results Serum levels of NPT were significantly higher in active JIA patients (10.7±21.7 nmol/l) than in the control group (4.98±2.01nmol/l; p<0,05). In remission, serum levels of NPT decreased significantly (4.34±2.3 nmol/l; p<0,001). In soJIA the levels of NPT was significantly higher than in patients with ERA onset (28.2 nmol/l vs 4.5 nmol/l; p<0,05). The levels of NPT showed no relationship with clinical and laboratory variables neither in active disease nor in remission.

Serum levels of sIL-2R were significantly higher in active JIA patients (8.9±12.8 ng/ml) than in the control group (1.8±1.6 ng/ml; p<0,001). In remission, the serum levels of sIL-2R decreased significantly (4.1±4.0 ng/ml; p=0,001). We found higher levels of sIL-2R in patients with clinically inactive disease (remission) in comparison to controls (p<0,001). In soJIA the levels of sIL-2R was significantly higher than in patients with POLY (31.4 vs 6.6; p<0,05).

Serum levels of sIL-2R of patients with active disease correlated with WBC and with parent/patient assessment of overall well-being. Serum levels of sIL-2R in remission correlated with ESR and negatively with Hgb.

Conclusions Serum levels of NPT and sIL-2R might be helpful markers for monitoring inflammation in JIA. To our knowledge, estimation of NPT in JIA, has not been published. NPT seems to be a useful parameter of cell-mediated immunity activation in JIA. The analysis showed serum NPT and sIL-2R concentrations differences between soJIA compared to the others. The elevated levels of sIL-2R in sera of patients in clinically remission suggest persistent activation of immune system and might be an indicator in adjusting the therapy. Longitudinal follow-up is required.

This work was funded by the Polish National Science Centre (Grant N N407 0382 37).

Disclosure of Interest None Declared