RESUMEN
OBJECTIVE: To determine the clinical value of assaying serum levels of neopterin, tumor necrosis factor-alpha (TNF-alpha) and soluble tumor necrosis factor receptor II (p75) (sTNFRII) in patients with systemic lupus erythematosus (SLE), manifested clinically with lupus nephritis (LN), neuropsychiatric lupus erythematosus (NPLE), and/or vasculitis compared with established parameters (complements C3 and C4). PATIENTS AND METHODS: Serum concentrations of neopterin, TNF-alpha and sTNFRII were studied in 40 female patients with SLE at various degrees of disease activity and in 10 healthy controls, matched for age and sex, using an ELISA kit. Disease activity was assessed by the SLE disease activity index (SLEDAI) score. Thirty-five, 30 and 28 of our patients presented with LN, NPLE and/or vasculitis, respectively, as the main clinical manifestation. RESULTS: Serum levels of neopterin, TNF-alpha and sTNFRII were significantly increased, while the TNF-alpha/sTNFRII ratio, C3 and C4 levels of SLE patients were significantly lower than those of healthy controls. Neopterin and sTNFRII were the only parameters that showed significantly higher levels in SLE patients with mild activity compared to normal subjects and were the only parameters that showed a significant elevation in membranous nephritis and in mild NPLE compared to patients without nephritis and NPLE. Patients with vasculitis had significant elevation of serum neopterin, TNF-alpha and sTNFRII levels compared to patients without vasculitis. We found significant correlations between all measured variables and the SLEDAI score. Also, serum neopterin levels showed significant positive correlation with serum TNF-alpha, sTNFRII and TNF-alpha/sTNFRII levels. Serum neopterin and sTNFRII could be used to identify SLE patients from normals with a sensitivity and specificity of 100%. Multivariate linear regression analysis showed that serum sTNFRII was the only significant independent variable among parameters for prediction of SLE disease activity. CONCLUSION: We suggest that serum sTNFRII and neopterin are more sensitive markers of disease activity than TNF-alpha, C3 or C4. However, sTNFRII may be a clinically useful independent marker for prediction of SLE disease activity and to differentiate normal subjects from those having mild SLE.
