Sandwich enzyme immunoassay for human interleukin-1 beta (hIL-1 beta) in urine

A highly sensitive sandwich enzyme immunoassay for human interleukin-1 beta (hIL-1 beta) in urine is described. Rabbit anti-hIL-1 beta IgG-coated polystyrene balls were incubated with urine samples and subsequently with affinity-purified rabbit anti-hIL-1 beta Fab'-horseradish peroxidase conjugate. After washing, the peroxidase activity bound to the polystyrene ball was assayed by fluorimetry using 3-(4-hydroxyphenyl)propionic acid as a substrate. The detection limit of hIL-1 beta was 0.5 pg/tube (30 amol/tube) or 5 ng/1 of urine when 0.1 ml of urine sample was used. The molecular weight of hIL-1 beta in normal urine was shown to be 17,000 by gel filtration, and levels of urine hIL-1 beta in healthy subjects aged 19-87 yr were 0-146 ng/1 or 0-88 ng/g of creatinine.