The production of interleukin (IL) -1 alpha IL-1 beta and IL-1 receptor antagonist (IL-1ra) by blood mononuclear cells (MNC), as well as the corresponding serum levels of IL-1ra were examined in blood samples from umbilical cords (n = 11), children (n = 40) and adults (n = 20), and in 42 patients with juvenile chronic arthritis (JCA) of the pauci- or polyarticular onset type.
IL-1ra serum levels were found to differ significantly between the three age groups, being higher in neonates (569 pg/ml) than in children (70 pg/ml) and adults (177 pg/ml). IL-1ra production in E. coli lipopolysacharide (LPS) stimulated-cultures of MNC was also significantly higher in neonates (median 2451 pg/ml) than in children (1526 pg/ml), but similar to that in adults (2107 pg/ml). IL-1ra levels in the sera of both subgroups of JCA patients were significantly elevated (median 257 pg/ml), but did not reflect paraclinical or clinical disease parameters. In samples of synovial fluid the IL-1ra levels tended to be fairly high, up to approximately 2 ng/ml, but they did not reflect the serum levels of IL-1ra.
These findings suggests that the upregulation of IL-1ra production forms part of the immunoregulatory response in JCA patients, and that the insufficient production of IL-1ra is unlikely to contribute to the pathogenesis of JCA.