passages.id: split_6_test_879_passage
passages.type: progene_text
passages.text: Plasma levels of interleukin-1beta ( IL-1beta ) , IL-2 , soluble IL-2 receptor ( sIL-2R ) , IL-6 , IL-8 , tumor necrosis factor - alpha ( TNF-alpha ) , and the p60 soluble TNF receptor ( sTNFR ) were repeatedly determined by enzyme - linked immunosorbent assays ( ELISA ) in 35 patients with different subtypes of juvenile rheumatoid arthritis ( JRA ) during an observation period of up to 36 months .