Objective: To analyse the circulating levels of Th1 and Th2 cytokines in patients with primary Sjögren's syndrome (SS), as well as to investigate their association with clinical and immunological manifestations.
Methods: We included 62 consecutive patients (58 women and 4 men) seen in our Unit. All patients fulfilled 4 or more of the European diagnostic criteria for SS. Serum levels of IL-6 (pg/mL), IL-2 (pg/mL), srIL-2 (pM), TNFalpha (pg/mL) and IL-10 (pg/mL) were determined using a solid phase enzyme immunoassav performed on microtiter plate.
Results: When compared with the control group, high levels of Th1 (11-2, srIL-2) and Th2 (IL-6, IL-10) cytokines were detected in SS patients, although only IL-6 levels reached statistical significance. On the other hand, analysis of the mean serum concentrations of cytokines showed distinct patterns of elevated cytokines according to the organ involved, and elevated levels of IL-6 (126.5 v 20.6 pg/mL, p < 0.05) and IL-10 (10.6 v 2.2 pg/mL, p < 0.005) were observed in those patients with liver involvement. Analysis of the cytokine levels according to the presence of immunological features showed: higher levels of srIL-2 (95.6 v 54.0 pM, p < 0.05) in patients with anti-Ro/SS-A antibodies; increased levels of srIL-2 (111.4 v 59.4 pM, p < 0.05) in patients with antiLa/SS-B antibodies; higher levels of srIL-2 (90.4 vs 50.8 pM, p < 0.05) and TNFalpha (37.9 v 22.6 pg/mL, p = 0.001) in patients with RF and higher levels of IL-6 (88.0 v 23.1 pg/mL, p < 0.05) in patients with cryoglobulins and in those with hypocomplementemia (130.3 vs 21.0 pg/mL, p < 0.05).
Conclusion: We found a significant elevation of several circulating cytokines in some clinical and immunological subsets of patients with primary SS. These cytokine patterns may be markers for specific extraglandular involvement in SS and could be of interest in assessing the response to treatment protocols or in monitoring the disease evolution.