[Fundamental studies on the measurement of urinary leukotriene E4]

We undertook fundamental studies on the measurement of urinary leukotriene E4, a stable end-product of peptidoleukotrienes, and obtained the following results. 1) After addition of 3H-LTE4 to 2 ml of urine, LTE4 was extracted with a commercial C18 mini-column, and purified by high performance liquid chromatography and then LTE4 in the elute was measured with an enzyme immunoassay kit. 2) As total recovery of LTE4 was 35.3 +/- 0.9% (n = 76), the amount of LTE4 was calculated after correction of the recovery with 3H-LTE4. 3) Before extraction of LTE4 by C18 column, the column was washed by ethyl acetate to remove interfering substances. This procedure greatly facilitated the following high performance liquid chromatographic analysis. 4) The basal levels of urinary LTE4 of seven aspirin-sensitive asthmatics were elevated as compared with five asthmatics without aspirin sensitivity (358.9 +/- 114.0 versus 77.9 +/- 47.3 pg/mg.cr; p < 0.05). 5) In two asthmatic patients, improvement of their symptoms was accompanied with decrease in the LTE4 level in urine. This method enabled us to measure LTE4 concentrations in a small volume of urine (2 ml), and would be useful for evaluating the pathogenesis of bronchial asthma.