SERIAL MEASUREMENTS OF SOLUBLE INTERLEUKIN-2 RECEPTOR LEVELS (SIL2-R)IN CHILDREN WITH JUVENILE RHEUMATOID-ARTHRITIS TREATED WITH ORAL METHOTREXATE

Objective-To investigate the potential clinical utility of serial leve ls of sIL2-R as a marker of disease activity among children with juven ile rheumatoid arthritis (JRA) treated with methotrexate (MTX). Method s-sIL2-R levels, measured by ELISA, were evaluated in 16 JRA patients (10 polyarticular, six systemic-onset) treated with oral, weekly MTX. sIL2-R values were compared with those of 49 normal controls. Medical record review was used to obtain relevant clinical data. Joint counts (number of swollen joints) were used as indicators of clinical change. A reduction of 50% in joint counts between pre and post treatment mea surements was considered a clinically significant response. Results-Th e mean(SEM) sIL2-R value of pre treatment JRA of 1728(290) U/ml was si gnificantly higher than the post treatment value of 921(229) U/ml (Wil coxon Rank test, p less than or equal to 0.001). Pre treatment values were also significantly different from the mean(SEM) of healthy contro ls of 519(19) U/ml (p < 0.001). Pre treatment sIL2-R levels of 2417(29 1) U/ml in systemic-onset JRA were significantly higher than sIL2-R va lues in polyarticular JRA patients of 1218(884) U/ml (Mann-Whitney ran k test p < 0.001). Among the 13/16 children with good therapeutic resp onses (greater than or equal to 50% improved), the range of sIL2-R dec reases was 154-2641 U/ml (mean 842 U/ml); sIL2-R levels increased in t he three children with poor clinical responses to methotrexate. Conclu sions-sIL2-R levels paralleled the course of disease in all patients. sIL2-R levels may be useful for monitoring therapeutic responses in ch ildren with JRA.