A second antibody solid-phase enzyme immunoassay of prostaglandin E2 in human gastric juice.

A second antibody solid-phase enzyme immunoassay for the determination of prostaglandin E2 in human gastric juice was developed using acetylcholine esterase as label, covalently coupled to the eicosanoid. The assay was performed on 96-well microtiter plates coated with the second antibody (swine antirabbit IgG antibody). The enzyme-labeled and unlabeled prostaglandin E2 were allowed to react in a competitive manner with the immobilized specific antibody (rabbit anti-prostaglandin E2 serum). After addition of the enzyme substrate, the specifically bound acetylcholine esterase was determined at 414 nm by means of a colorimetric assay and the enzyme activity was correlated with the amount of unlabeled prostaglandin E2. According to the calibration curve, prostaglandin E2 was determined in the range of 0.5-250 pg/ml. The minimal detectable concentration of prostaglandin E2 was 1.9 +/- 0.2 pg/ml. The intraassay coefficient of variation was less than 10%. Most prostaglandins and their metabolites tested showed a cross-reactivity of less than 1%.