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Validation and application of a new simple strategy for measurements of urinary leukotriene E 4 in humans
Author(s) -
KUMLIN M.,
STENSVAD F.,
LARSSON L.,
DAHLÉN B.,
DAHLEN S.E.
Publication year - 1995
Publication title -
clinical and experimental allergy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 154
eISSN - 1365-2222
pISSN - 0954-7894
DOI - 10.1111/j.1365-2222.1995.tb01079.x
Subject(s) - urine , urinary system , immunoassay , leukotriene e4 , chromatography , metabolite , chemistry , leukotriene , radioimmunoassay , asthma , medicine , immunology , biochemistry , antibody
Summary To monitor endogenous production of cysteinyl‐containing leukotrienes, the end‐metabolite leukotriene E 4 (LTE 4 ) was analysed in urine. Results obtained with a sensitive enzyme immunoassay (EIA), performed on crude urine samples correlated well with data obtained from a previously reported radioimmunoassay. Enzyme immunoassay analysis of unextracted urine was justified by an excellent agreement between analyses in crude samples and measurements achieved after purification on solid phase extraction followed by separation on reversed‐phase high performance liquid chromatography. Moreover, LTE 4 was stable in urine samples stored at ‐20°C, for months without the addition of preservatives. The stability of LTE 4 in urine was not improved by addition of the antioxidant 4‐hydroxy‐TEMPO and pH adjustment to 9. As assessed by EIA analysis in crude urine samples, baseline values for urinary leukotriene E 4 were not significantly different between atopic asthmatic subjects and non‐asthmatic individuals, and there was no diurnal variation in urinary excretion of LTE 4 in healthy subjects. However, we confirmed earlier data on significantly higher basal levels of urinary LTE 4 in aspirin‐intolerant asthmatics. In addition, a post‐challenge increase in urinary LTE 4 levels was detected in association with allergeninduced airway obstruction in atopic asthmatics. The per cent increase in urinary LTE 4 was similar, irrespective of whether the samples were purified or not prior to EIA. Thus, combined with random validation by high performance liquid chromatography, the strategy of direct EIA of serially diluted urine samples was found to be a good index of in vivo production of leukotrienes. This was further reinforced by the demonstration that pretreatment with the leukotriene biosynthesis inhibitor Bay × 1005 inhibited the post allergen‐challenge increase in urinary LTE 4 , as shown both with unpurilied and purified samples.