Tumour necrosis factor alpha and its soluble receptors in juvenile chronicarthritis

Objective. To identify possible imbalance of tumour necrosis factor alpha ( TNF alpha) and its soluble receptors in the different subgroups of juvenile chronic arthritis (JCA). Methods. Serum and synovial fluid samples from 45 children were examined, 2 5 pauciarticular JCA, 13 polyarticular JCA and seven spondyloarthropathy. T NF alpha, sTNFRI and sTNFRII levels were measured by EASIA and enzyme-linke d immunosorbent assay (ELISA). Analysis of the results was carried out usin g non-parametric tests: Kruskal-Wallis one-way analysis of variance was use d to compare the three clinical subgroups: the MannWhitney U-test was used to compare group medians. Results. Thirty-three serum samples were assayed for TNF alpha. There was n o significant difference between the three groups using the Kruskal-Wallis analysis of variance. Analysis of synovial fluid TNF levels showed signific antly lower levels in the spondyloarthropathy group compared with the pauci articular JCA (P = 0.01) and the polyarticular group (P = 0.001). Significa ntly higher levels of sTNFRI were observed in the synovial fluid of the pol yarticular JCA group compared with the pauciarticular JCA group (P = 0.004) and similarly for sTNFRII (P = 0.03). Molar ratios were calculated for TNF , vs sTNFRI. The sTNFRI/TNF alpha ratio was significantly higher in the spo ndyloarthropathy group compared with the pauci(P = 0.003) and the polyartic ular JCA subgroups (P = 0.003). The combined soluble receptor levels expres sed as molar ratio to TNF again showed a significantly higher ratio in the spondyloarthropathy group compared with the pauciarticular group (P = 0.01) and compared with the polyarticular group (P = 0.05). Conclusion. These results suggest that the increased joint destruction obse rved ill polyarticular disease compared with the other two subtypes may be related to the lower sTNFR/TNF alpha ratios observed.