INTERLEUKIN-1-BETA MEDIATED CALCIOTROPIC ACTIVITY IN SERUM OF CHILDREN WITH JUVENILE RHEUMATOID-ARTHRITIS

Objective. To detect the presence and source of calciotropic activity in the serum of children with juvenile rheumatoid arthritis (JRA). Met hods. Metabolic evaluation of an adolescent with polyarticular JRA and hypercalcemia/hypercalciuria included testing with a bone disc bioass ay. The bioassay detects calciotropic activity (increased bone resorpt ion or reduced bone formation) in serum. Interleukin 1 receptor antago nist (IL-1RA) was added to patient sera to test the role of IL-1 beta. The results in this index case prompted additional study in 9 childre n with JRA, Correlation of calciotropic activity with disease activity score, erythrocyte sedimentation rate (ESR), and urinary calcium excr etion was by Spearman rank correlation. Results. Calciotropic activity was found in 2 consecutive samples from the index patient. This activ ity was eliminated by addition of IL-1RA (p < 0.001 compared to serum alone). Testing of the other 9 children showed calciotropic activity a t least once in 7/9 and 10/15 samples studied. Addition of IL-1RA comp letely (6/8) or partially (2/8) neutralized calciotropic activity (p < 0.001 compared to serum alone) in the specimens available for testing . Calciotropic activity did not significantly correlate with disease a ctivity score, ESR, or urine calcium. Conclusion. Our data indicate th e presence of IL-1 beta mediated calciotropic activity in the sera of children with JRA, and suggest a role for IL-1 beta in JRA associated osteopenia.