Endogenous synthesis of cysteinyl leukotrienes in juvenile rheumatoid arthritis (JRA) was investigated.
Cysteinyl leukotriene synthesis was assessed by measuring the excretion of leukotriene E4 (LTE4) in urine by radioimmunoassay. The identity of urinary LTE4 was investigated by gas chromatography-mass spectrometry (GC-MS), and 2,3-dinor-thromboxane B2 was measured with GC-MS.
Excretion of LTE4 into urine was significantly (P < 0.05) enhanced in children with JRA compared with that in healthy children (n = 10). Aspirin, in a dosage of 2.5 gm/day, had no effect on urinary LTE4 levels, but it reduced urinary 2,3-dinorthromboxane B2 levels by more than 85% in healthy adults. There was a positive correlation between LTE4 excretion and the number of affected joints.
This study demonstrates a markedly enhanced cysteinyl leukotriene synthesis and a positive correlation between LTE4 excretion and the number of affected joints in children with JRA.