Serum IL-6, TNFα, p55 srTNFα, p75 srTNFα, srIL-2α levels and disease acitivity in systemic lupus erythematosus

The aim of this study was to determine whether the levels of serum cytokines IL-6 and TNF alpha and of the soluble receptors p55 srTNF alpha, p75 srTNF alpha and srIL-2 alpha an valuable markers of disease activity in patients with systemic lupus erythematosus (SLE) compared with the established parameters of anti-dsDNA, C3, C4 and CH50. Forty patients with SLE, 19 ambulatory and 21 hospitalised, were included in this study. On the day of blood sampling a clinical examination was performed and SLEDAI and ECLAM disease activity scores were used to assess disease activity. Nineteen patients had inactive disease and 21 patients had active disease. Thirteen patients from the second group developed nephritis. In these patients the blood sampling and disease activity assessment were performed twice (at presentation and 6 months after treatment). Serum levels of cytokines and soluble receptors were measured by ELISA. Serum levels of cytokines and soluble receptors of patients with active disease were significantly higher than in patients with inactive disease (IL-6 p = 0.0004, TNF alpha p = 0.0015, srIL- 2 alpha p<0.0001, p55 srTNF alpha p<0.0001, p75 srTNF alpha p<0.0001). Serum soluble receptor levels of patients with inactive disease were higher than those of healthy controls (p55 srTNF alpha p < 0.0001, p75 srTNF alpha p = 0.0002, srIL-2 alpha p = 0.0012). No significant difference was found for TNF alpha and IL-6 (TNF alpha p = 0.015, IL-6 p = 0.019). Serum TNF alpha levels and especially srIL-2 alpha, p55 srTNF alpha and p75 srTNF alpha levels correlated strongly with SLEDAI and ECLAhl disease activity scores, anti-dsDNA, C3, C4 and CH50 (p < 0.0001). Serum soluble receptor (srIL-2 alpha, p55 srTNF alpha, p75 srTNF alpha) levels were higher in patients with nephritis before treatment and decreased significantly 6 months after treatment (p = 0.005). The same trend was noticed with SLEDAI and ECLAM disease activity scores (p = 0.005) and anti dsDNA (p = 0.008). In contrast, no significant differences were observed for C3 and C3 levels before and after treatment, which suggests that soluble receptors of cytokines are more sensitive markers of disease activity than C3 or C4 in predicting improvement. Serum levels of srIL-2 alpha, p55 srTNF alpha and p75 srTNF alpha could provide useful information about disease activity in SLE patients, especially in cases where the other markers do not.