To investigate clinical significance of tumor necrosis factor-alpha (TNF-alpha) and kidney damage in patients with rheumatoid arthritis (RA).
94 patients (84 women and 10 men, mean age 45.2 +/- 11.9 years and the disease duration 7.5 +/- 6.5 years) with RA and 20 donors were examined. In 37(39.4%) and 57(60.6%) patients radiological stages I-II and III-IV, respectively, were determined. TNF-alpha and C-reactive protein (CRP) were measured by ELISA.
Serum levels of TNF-alpha in patients with RA appeared significantly higher than in donors (10.9 +/- 22.1 pg/ml vs 0.6 +/- 2.0 pg/ml, p < 0.001). 33 (35.1%) of 94 patients had TNF-alpha levels above 6.6 pg/ml. High serum levels of TNF-alpha correlated significantly with the presence of nephrotic syndrome (r = 0.22, p = 0.03) caused by secondary amyloidosis. There were no correlations between high levels of TNF-alpha and sex, age, disease duration, stages and clinical activity in patients with RA. Positive correlation was found between high levels of TNF-alpha and ESR (r = 0.30, p = 0.003), CRP (r = 0.37, p = 0.0001).
Thus, TNF-alpha may be involved in pathogenesis of amyloidosis in RA.