Limit of detection: 80% B/B₀: 25 pg/ml · Sensitivity: 50% B/B₀: 100 pg/ml · Leukotriene E₄ (LTE₄) is a product of the 5-lipoxygenase (5-LO) pathway in activated mast cells, eosinophils, and monocytes.¹ LTA₄, the primary 5-LO metabolite, is converted to LTC₄ and sequentially to LTD₄ and LTE₄ in the host cell, or by transcellular metabolism in erythrocytes, platelets, or neutrophils. This metabolism is rapid and complete, in that plasma levels of LTC₄ are virtually undetectable. Exogenously administered LTC₄ is recovered in the urine as LTE₄ (5-13%) and two prominent oxidized metabolites resulting from several cycles of β-oxidation.² The plasma half-life of is about 7 minutes. Plasma LTE₄ levels are likewise <2 pg/ml as a consequence of the low rate of production and rapid elimination.³ Normal human urine contains low but detectable amounts of LTE₄, ranging from 10-60 pg/ml.⁴ Asthmatic patients in an acute episode of bronchoconstriction may have elevations of urinary LTE₄ to several hundred pg/ml, but their baseline LTE₄ levels are not consistently abnormal. Methods for the rapid isolation and detection of LTE₄ from human urine have been developed.^5,6

1 Maclouf, J., Antoine, C., De Caterina, R., et al. Entry rate and metabolism of leukotriene C₄ into vascular compartment in healthy subjects. Am J Physiol 263 H244-H249 (1992).

2 Sala, A., Voelkel, N., Maclouf, J., et al. Leukotriene E₄ elimination and metabolism in normal human subjects. J Biol Chem 265 21771-21778 (1990).

3 Huber, M., Müller, J., Leier, I., et al. Metabolism of cysteinyl leukotrienes in monkey and man. Eur J Biochem 194 309-315 (1990).

4 Kumlin, M., Stensvad, F., Larsson, L., et al. Validation and application of a new simple strategy for measurements of urinary leukotriene E₄ in humans. Clin Exp Allergy 25 467-479 (1995).

5 Westcott, J.Y., Sloan, S., and Wenzel, S.E. Immunofiltration purification for urinary leukotriene E₄ quantitation. Anal Biochem 248 202-210 (1997).

6 Westcott, J.Y., Maxey, K.M., MacDonald, J., et al. Immunoaffinity resin for purification of urinary leukotriene E₄. Prostaglandins Other Lipid Mediat 55 301-321 (1998).

Huber, M., Müller, J., Leier, I., et al. Metabolism of cysteinyl leukotrienes in monkey and man. Eur J Biochem 194 309-315 (1990).

Sala, A., Voelkel, N., Maclouf, J., et al. Leukotriene E₄ elimination and metabolism in normal human subjects. J Biol Chem 265 21771-21778 (1990).

Pradelles, P., Antoine, C., Lellouche, J., et al. Enzyme immunoassays for leukotrienes C₄ and E₄ using acetylcholinesterase. Methods Enzymol 187 82-89 (1990).

Fradin, A., Zirrolli, J.A., Maclouf, J., et al. Platelet-activating factor and leukotriene biosynthesis in whole blood. A model for the study of transcellular arachidonate metabolism. J Immunol 143 3680-3685 (1989).

Maclouf, J., Antoine, C., De Caterina, R., et al. Entry rate and metabolism of leukotriene C₄ into vascular compartment in healthy subjects. Am J Physiol 263 H244-H249 (1992).

Kumlin, M., Stensvad, F., Larsson, L., et al. Validation and application of a new simple strategy for measurements of urinary leukotriene E₄ in humans. Clin Exp Allergy 25 467-479 (1995).

Westcott, J.Y., Sloan, S., and Wenzel, S.E. Immunofiltration purification for urinary leukotriene E₄ quantitation. Anal Biochem 248 202-210 (1997).

Westcott, J.Y., Maxey, K.M., MacDonald, J., et al. Immunoaffinity resin for purification of urinary leukotriene E₄. Prostaglandins Other Lipid Mediat 55 301-321 (1998).

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