Urinary Leukotriene E4 Research Articles

Urinary Leukotriene E4 Levels Are Not Increased Prior to High-Altitude Pulmonary Edema

To examine whether increased urinary cysteinyl-leukotriene E(4) (LTE(4)) excretion, which has been found to be elevated in patients presenting with high-altitude pulmonary edema (HAPE), precedes edema formation. Prospective studies in a total of 12 subjects with susceptibility to HAPE. In a chamber study, seven subjects susceptible to HAPE and five nonsusceptible control subjects were exposed for 24 h to an altitude of 450 m (control day), and exposed for 20 h to 4,000 m after slow decompression over 4 h. In a field study, prospective measurements at low and high altitude were performed in five subjects developing HAPE at 4,559 m. Mountaineers with a radiographically documented history of HAPE and control subjects who did not develop HAPE with identical high-altitude exposure. 24-h urine collections. In the hypobaric chamber, none of the subjects developed HAPE. The 24-h urinary LTE(4) did not differ between HAPE susceptible and control subjects, nor between hypoxia and normoxic control day. In the field study, urinary LTE(4) was not increased in subjects with HAPE compared to values obtained prior to HAPE at high altitude and during 2 control days at low altitude. These data do not provide evidence that cysteinyl-leukotriene-mediated inflammatory response is associated with HAPE susceptibility or the development of HAPE within the context of our studies.

The challenge procedure influences the extent of allergen-induced urinary excretion of leukotriene E4.

Cysteinyl-leukotrienes are central mediators in asthma and urinary leukotriene E4 (LTE4) is a reliable marker of their endogenous formation. This study tested the hypothesis that the procedure used for allergen bronchoprovocation influences the bronchoconstrictor response and the amount of LTE4 excreted following allergen challenge. Seven atopic asthmatic men underwent two allergen bronchoprovocations 4 weeks apart. The same total dose of allergen was given at both sessions, cumulatively on one occasion and as a single dose at the other session. Urine was collected in hourly samples before and after challenge and LTE4 was measured with previously validated methodology. The mean (+/- SE) drop in FEV1 was not significantly different between the cumulative (29 +/- 2.4%) and the single dose challenge (25 +/- 2.8%). There was a significant increase in post-challenge levels of urinary LTE4 after both sessions. The peak excretion of LTE4 occurred 1 h following the maximal drop in FEV1 for both challenges. However, the post-challenge increase in urinary LTE4 was significantly larger at the cumulative session. In fact, the net increase (post-challenge minus prechallenge) of urinary LTE4 was more than twofold higher after the cumulative session (AUC 0-3 h post-challenge: 46.7 +/- 8.2 vs 22.1 +/- 9.8, P < 0.05). The peak excretion of urinary LTE4 occurred within 2 h after the termination of either challenge but the magnitude of urinary excretion of LTE4 was larger when cumulative challenge was performed. The findings are important to consider when designing studies where allergen-induced urinary excretion of LTE4 is an outcome variable.

Early increase in urinary leukotriene E4 (LTE4) is dependent on allergen dose inhaled during bronchial challenge in asthmatic subjects.

Urinary leukotriene E4 (LTE4) excretion is a good marker of the rate of total body production of sulfidopeptide leukotrienes released during allergen challenge. Twenty-three subjects with allergic asthma were challenged with inhaled allergen, and the urinary excretion of LTE4 was determined by immunoenzymatic assay (associated with HPLC separation) at various intervals after challenge. Allergen challenge caused an early airway response (EAR) with a drop in FEV1 of 40.3+/-9.9%. This was associated with an increase in urine LTE4 excretion for 0-3 h after allergen inhalation (296+/-225.25 pg/mg creatinine) in comparison with baseline values obtained during the night before challenge (101.02+/-61.97 pg/mg creatinine). Urinary LTE4 excretion was significantly higher in subjects who inhaled a higher dose of allergen during challenge (LTE4 during EAR: 211+/-192 pg/mg creatinine in subjects with inhaled total dose of allergen <0.1 biologic units; 408+/-223 pg/mg creatinine in subjects with inhaled total dose >0.1 biologic units). All subjects showed a late airway response (LAR) to allergen of different severity, from mild (FEV1 fall: 15-20%) to severe (>30%); no correlation was found between the increase in urine LTE4 excreted during LAR (3-7 h after challenge) and the severity of LAR, but only subjects with severe LAR showed a significant increase in LTE4 during LAR in comparison with baseline value. A release of sulfidopeptide leukotrienes, as evaluated by urinary LTE4 excretion, can be documented during EAR and LAR to allergen in relation to the dose of inhaled allergen, and it can represent a useful index of the events underlying the airway inflammatory responses during allergen challenge.

Bronchial Hyperresponsiveness, Hypersensitivity to Analgesics and Urinary Leukotriene E4 Excretion in Patients with Aspirin–Intolerant Asthma

This study was designed to investigate the protective effect of cromolyn sodium on airway sensitivity to sulpyrine, and bronchial responsiveness to methacholine, and to investigate whether this protective activity is associated with reduction in aspirin–induced excretion of urinary leukotriene E₄ (u–LTE₄), a marker of the cysteinyl LT overproduction that participates in the pathogenesis of aspirin–induced asthma. We assessed the effects of pretreatment with cromolyn sodium on bronchoconstriction precipitated by inhalation of methacholine and sulpyrine in 16 adult patients with mild or moderate aspirin–intolerant asthma; those who were in stable clinical condition and were hypersensitive to a sulpyrine provocation test were included in this study. A double–blind, randomized, crossover design was used. u–LTE₄ was measured using combined reverse–phase high–performance liquid chromatography enzyme immunoassay. Cromolyn sodium protected against analgesic–induced bronchoconstriction through mechanisms that are not related to its bronchodilator property, but to the improvement of both bronchial hyperresponsiveness and hypersensitivity to analgesics (p<0.01 and p<0.001). Although excretion of u–LTE₄ did not increase after the methacholine provocation test, it significantly increased after sulpyrine provocation (p<0.01). Furthermore, after pretreatment with cromolyn sodium, the maximum level of u–LTE₄ after the sulpyrine provocation test was significantly lower than in controls (p<0.01). These results support the hypothesis that cysteinyl LT is one of the most important components in the pathogenesis of aspirin–intolerant asthma. Cromolyn sodium improves both hypersensitivity to analgesics, and bronchial hyperresponsiveness in aspirin–intolerant asthma.

Correlation among urinary eosinophil protein X, leukotriene E4, and 11-dehydrothromboxane B2 in patients with spontaneous asthmatic attack.

Various kinds of cells and their mediators are thought to be involved in the pathogenesis of bronchial asthma. However, changes in each mediator or relationship among mediators during an asthmatic attack have not been well documented. In this study, to clarify whether eosinophil protein X (EPX) is a marker which is distinct from leukotriene E4 (LTE4), or 11-dehydrothromboxane B2 (11DTXB2), we measured the urinary excretion of EPX, LTE4, and 11DTXB2 in 14 asthmatics who were admitted to the hospital with either an acute asthmatic attack or status asthmaticus. These patients included eight atopic and six non-atopic types of bronchial asthma, with a median age of 34.0 years. Urinary excretion of EPX was significantly high on admission with the asthmatic attack, and returned to control levels 175 [122 -384] microg/day when the patients were in the improved state (1036-317 microg/day, P < 0.01). Similar findings were observed in LTE4 (155-59 ng/day, P < 0.01) and 11DTXB2 (991-442ng/day, P<0.01). No significant differences in values were observed between atopic and non-atopic types of asthma in all three substances. When the individual data during the attack state were analysed, a significant correlation was observed between changes (%) in urinary EPX and those in urinary LTE4, but no such relationship was observed between changes (%) in urinary EPX and those in urinary 11DTXB2. These results suggest that measuring urinary EPX levels may be a useful marker for the understanding and management of the disease.

Effects of a 5-lipoxygenase inhibitor, ABT-761, on exercise-induced bronchoconstriction and urinary LTE4 in asthmatic patients

The novel 5-lipoxygenase (5-LO) inhibitor, ABT-761, was investigated for its effect on exercise-induced bronchoconstriction in asthmatic subjects. The relationship between 5-LO inhibition and effects on the response of the airways to exercise was examined. In a double-blind, randomized, crossover clinical trial, 10 patients with mild to moderate persistent asthma (who exhibited a fall in forced expiratory volume in one second (FEV1) > or = 20% following standardized exercise challenge) received 200 mg ABT-761 or matched placebo, orally, 5 h prior to exercise on two study days, 7-10 days apart. Lung function, urinary leukotriene E4 (LTE4) and ex vivo calcium ionophore-stimulated LTB4 release in whole blood were measured prior to dosing, prior to exercise and at various time points up to 4 h post-exercise. The mean (SD) maximal percentage fall in FEV1 after exercise was 27.1 (12)% on placebo and 19.9 (10)% on ABT-761 days, respectively (p<0.05). Post-exercise fall in FEV1 was significantly attenuated at 5, 10, 15 and 30 min after exercise and the mean area under curve, representing the overall effect of exercise from 0-45 min post-challenge, was also significantly attenuated by ABT-761 (p<0.001). Ex vivo LTB4 release was inhibited by more than 80% throughout the 4 h post-exercise period, indicating that 5-LO was extensively inhibited at all time points. Urinary LTE4 in the post-exercise period was significantly lower after ABT-761 day than after placebo (40.1 (17.6) versus 89.8 (58.2) pg x mg creatinine(-1); p<0.05). Inhibition of LTB4 release in ABT-761-treated patients correlated positively with the attenuation of post-exercise FEV1 decline (r=0.711; p<0.05). We conclude that ABT-761 is effective in suppressing exercise-induced bronchoconstriction and that this protection is related quantitatively to the degree of 5-lipoxygenase inhibition.

Cromolyn Sodium Prevents Bronchoconstriction and Urinary LTE4 Excretion in Aspirin-Induced Asthma

Inhalation of cromolyn sodium protects against sulpyrine-induced bronchoconstriction and prevents urinary leukotriene E4 (u-LTE4) excretion in aspirin-induced asthma. This study was designed to investigate the protective effect of cromolyn sodium on airway responsiveness to the sulpyrine provocation test, and to investigate whether this protective activity is associated with a reduction in aspirin-induced urinary excretion of LTE4, a marker of the cysteinyl leukotriene overproduction that participates in the pathogenesis of aspirin-induced asthma. We evaluated the effects of pretreatment with cromolyn sodium on bronchoconstriction precipitated by inhalation of sulpyrine in ten adult patients with mild aspirin-induced asthma. Those who were in stable clinical condition and were hyperresponsive to sulpyrine provocation test were allocated to this study. Urinary leukotriene E4 was measured using combined reverse phase high performance liquid chromatography (rp-HPLC)/enzyme immunoassay. Inhaled cromolyn sodium protects against aspirin-induced attacks of asthma through mechanisms not related to the bronchodilator property, but related to the improvement of the bronchial hypersensitivity, almost completely in all patients (P < .001). By contrast, after cromolyn sodium the maximum level of u-LTE4 was significantly lower than control (P < .05). Our results suggest for the first time that inhaled cromolyn sodium is one of the most useful inhibitors of aspirin-induced bronchoconstriction, probably acting by inhibiting the release of cysteinyl leukotrienes, and possibly other chemical mediators, by bronchial inflammatory cells.

Enhanced excretion of urinary leukotriene E4 in mevalonic aciduria is not caused by an impaired peroxisomal degradation of cysteinyl leukotrienes.

Journal of Inherited Metabolic DiseaseVolume 20, Issue 5 p. 721-722 Article Enhanced excretion of urinary leukotriene E4 in mevalonic aciduria is not caused by an impaired peroxisomal degradation of cysteinyl leukotrienes E. Mayatepek, E. Mayatepek Division of Metabolic Diseases, University Children's Hospital, Heidelberg, GermanySearch for more papers by this authorB. Tiepelmann, B. Tiepelmann Division of Metabolic Diseases, University Children's Hospital, Heidelberg, GermanySearch for more papers by this authorG.F. Hoffmann, G.F. Hoffmann Department of Neuropediatrics and Metabolic Diseases, University Children's Hospital, Marburg, GermanySearch for more papers by this author E. Mayatepek, E. Mayatepek Division of Metabolic Diseases, University Children's Hospital, Heidelberg, GermanySearch for more papers by this authorB. Tiepelmann, B. Tiepelmann Division of Metabolic Diseases, University Children's Hospital, Heidelberg, GermanySearch for more papers by this authorG.F. Hoffmann, G.F. Hoffmann Department of Neuropediatrics and Metabolic Diseases, University Children's Hospital, Marburg, GermanySearch for more papers by this author First published: 01 September 1997 https://doi.org/10.1023/A:1005351215690Citations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume20, Issue5September 1997Pages 721-722 RelatedInformation

Immunofiltration Purification for Urinary Leukotriene E4 Quantitation

Leukotriene E4 (LTE4) is a major leukotriene metabolite in urine. Urinary LTE4 concentration is often utilized as an index of total leukotriene synthesis. A novel method employing immunofiltration for the purification of urinary LTE4 was developed. This immunofiltration method is based upon the addition of excess anti-LTE4 antibody to urine which binds LTE4. Separation of bound LTE4 (highMr) from high levels of unbound contaminants (lowMr) is then accomplished by filtration through a 10,000Mrcut-off filter. The LTE4–antibody complex is separated by precipitation of the antibody with methanol which is subsequently removed by centrifugation. Following evaporation of the methanol, enzyme immunoassay is utilized for quantitation. This methodology was validated by determining the recovery of tritiated and unlabeled LTE4 added to urine and buffer and by comparison of results obtained with urine samples measured after HPLC purification (correlationr2= 0.72). Reproducibility of the assay was assessed by analyzing the same sample on two different days (standard deviation of 18%). The mean urinary LTE4 levels in healthy subjects and asthmatics measured utilizing this method were found to be identical to levels determined by HPLC/immunoassay. The ease and accuracy of this assay make it amenable for the analysis of large numbers of samples.

Efficient method for the quantitation of urinary leukotriene E4: extraction using an Empore C18 disk cartridge.

We describe here an efficient procedure for the precise quantitation of leukotriene E4 (LTE4) in a small volume of urine, which was achieved mainly by the use of an Empore extraction disk cartridge. After addition of [3H]LTE4 to 2 ml of urine, an Empore C18 cartridge was used for initial extraction of the urine, which resulted in the extraction of LTE4 in a small volume of solvent. The eluate could then be injected onto a high-performance liquid chromatography column without further concentration. After separation by high-performance liquid chromatography, LTE4 was extracted from the effluent using an Empore C18 cartridge. The concentration of LTE4 was subsequently quantified by enzyme immunoassay. LTE4 can be recovered from urine with sufficient efficiency (69.9+/-4.7%, mean+/-S.D., n=101). The coefficient of variation of the assay procedure was less than 10%. When urine was spiked with different amounts of LTE4, the recovery of LTE4 added to the urine specimen was less than 120%. The concentration of LTE4 in urine from normal healthy subjects was 48.0+/-15.3 pg/mg creatinine (n=15).

Urinary leukotriene E4 levels in patients with atopic dermatitis

Leukotriene synthesis may be increased in a variety of inflammatory diseases. Urinary leukotriene E4 is a stable metabolite of leukotrienes C4 and D4 which has previously been found to be increased in exacerbations of severe asthma and after antigen inhalation. Levels of urinary LTE4 in seven patients during and after a severe flare of atopic dermatitis were measured by high-performance liquid chromatography (HPLC) and radioimmunoassay (RIA). Mean urinary LTE4 levels (+/- SEM) were not increased during (16.7 +/- 3.7 pg/mumol) or after (16.9 +/- 4.8 mumol) the acute exacerbation of atopic dermatitis when compared with the normal range (mean = 23.8 [95% confidence interval 19.9-28.2] pg/mumol creatinine). These findings do not provide evidence of cysteine leukotriene involvement in the pathogenesis of atopic dermatitis.

Urinary leukotriene E4 and 11‐dehydrothromboxane B2 in patients with aspirin‐sensitive asthma

The objective of this study was to define the participation of cysteinyl leukotrienes (LTs) or thromboxane A2 in the pathogenesis of aspirin-sensitive asthma (ASA). Leukotriene E4 (LTE4) and 11-dehydrothromboxane B2 (11DTXB2) values in spot urine were measured in 22 asthmatics with a history of aspirin sensitivity and in 17 without such a history (non-aspirin-sensitive asthma [NASA]) in the outpatient clinic. The urinary LTE4 value was significantly higher in ASA patients than in NASA (340 +/- 47 vs 65 +/- 15 pg/mg.cr, P < 0.001), but there was no significant difference in urinary 11DTXB2 between the two groups (891 +/- 77 vs 657 +/- 90 pg/mg.cr). A high value of LTE4 was not associated with type of asthma, severity of disease, oral prednisolone treatment, sex, or age. A higher value of 11DTXB2 was observed in the atopic type than the nonatopic type in ASA (1086 +/- 111 vs 697 +/- 147 pg/mg.cr, P < 0.05). No correlation was observed between urinary LTE4 and 11DTXB2 in either ASA or NASA. In conclusion, LTs may play an important role in the pathogenesis of ASA, and TXA2 in the pathogenesis of the atopic type in ASA.

Cigarette smoking stimulates cysteinyl leukotriene production in man.

Chronic cigarette smoking is an important risk factor for pulmonary and cardiovascular diseases. An increased production of cysteinyl leukotrienes has been shown in asthma and in cardiac ischaemia. The effect of cigarette smoking on cysteinyl leukotriene biosynthesis is, however, not known. Urinary leukotriene E4 (LTE4) was measured in 30 habitual smokers and in 30 non-smokers. In a further 12 non-smokers urinary LTE4 excretion was assessed before and after smoking six cigarettes. In addition, the effect of transdermal nicotine on urinary LTE4 excretion was studied in seven non-smokers. There was a close correlation (r = 0.92, P < 0.0001) between urinary excretion of LTE4 and the number of cigarettes smoked daily by habitual smokers. Smoking six cigarettes within 12h resulted in a significant (P = 0.0047), twofold increase in the mean individual LTE4 excretion in non-smokers. Transdermal nicotine had no effect on LTE4 excretion in non-smokers. In conclusion, cigarette smoke causes a dose-related increase in cysteinyl leukotriene production in habitual smokers. Some of the adverse effects of smoking may be related to an enhanced leukotriene synthesis.

Simultaneous determination of cross-reactive leukotrienes in biological matrices using on-line liquid chromatography immunochemical detection.

Sulfidopeptide leukotrienes, which are important biomarkers for several diseases, are commonly measured by microtiter plate immunoassays. These immunoassays, however, cannot distinguish between several structurally similar leukotrienes and their cross-reactive metabolites and, therefore, need extensive sample handling and fractionation by means of liquid chromatography (LC). This paper describes the development and automation of a continuous-flow immunochemical detection (ICD) system and its subsequent on-line coupling to LC. The on-line LC-ICD system based on fluorescence-labeled leukotriene E4 (LTE4) was used to determine sulfidopeptide leukotrienes and their cross-reactive metabolites in a single run. Furthermore, biological matrices, e.g., urine and human cell extracts, were analyzed, the only sample pretreatment being on-line solid-phase extraction (SPE) on a novel RP-C4 restricted-access support. The determination limit of LTE4 in urine was 0.2 ng/mL (800 fmol; injection volume, 2000 microL; signal-to-noise ratio, 10). The system was linear from 0.2 to 1.0 ng/mL LTE4. Using nonlinear curve-fitting, the range could be expanded to 2.5 ng/mL. It is shown that, besides quantitation of known analytes, on-line LC-ICD is useful in the discovery of cross-reactive LTE4 metabolites.

Urinary Leukotriene E4 Levels in High-Altitude Pulmonary Edema: A Possible Role for Inflammation

<h3>Study objectives</h3> Inflammation may contribute to the pathogenesis of high-altitude pulmonary edema (HAPE). This study was designed to determine whether a marker of inflammation, urinary leukotriene E4 (LTE4), is elevated in patients with HAPE. <h3>Design</h3> We conducted a case-control study to collect clinical data and urine samples from HAPE patients and healthy control subjects at moderate altitude (≥2727 m), and follow-up urine samples from HAPE patients following their return to low altitude (≤1,600 m). <h3>Setting</h3> Five medical clinics in Summit County, Colorado. <h3>Patients</h3> Questionnaire data were evaluated in 71 HAPE patients and 36 control subjects. Urinary LTE4 levels were determined from a random subset of 38 HAPE patients and 10 control subjects presenting at moderate altitude, and on 5 HAPE patients who had returned to low altitude. <h3>Measurements and Results</h3> Using an enzyme immunoassay technique, urinary LTE4 levels were found to be significantly higher in HAPE patients (123 [16 to 468] pg/mg creatinine, geometric mean [range]) than in control subjects (69 [38 to 135]), p=0.02. Following return to low altitude, urinary LTE4 levels fell significantly from 122 (41.8 to 309) to 53.6 (27.6 to 104) pg/mg creatinine (p=0.05). Urinary LTE4 levels were not related to age, sex, time at altitude, physical condition or habitual exercise, recent use of alcohol or nonsteroidal anti-inflammatory drugs (NSAIDs), or oxygen saturation. Clinical factors associated with HAPE included male sex, regular exercise, and recent use of NSAIDs. <h3>Conclusions</h3> We conclude that urinary LTE4 levels are elevated in patients with HAPE, supporting the view that HAPE involves inflammatory mechanisms.

Urinary Leukotriene E4 Levels Increase Upon Exposure to Hypobaric Hypoxia

To determine whether urinary leukotriene E4 (uLTE4) levels increase upon exposure to high altitude, and also to ascertain the relationship between uLTE4 levels and symptoms of acute mountain sickness (AMS). Prospective, unblinded, single-factor (altitude) experimental study. US Army research laboratory facilities at sea level ([SL] 50 m), 1,830 m, and 4,300 m. Eight healthy male subjects ranging in age from 19 to 24 years. uLTE4 levels and symptoms of AMS were measured at just above SL (50 m), 3 1/2 days after being transported from SL to moderate altitude (MA) (1,830 m), and 1 1/2 days after ascent from 1,830 to 4,300 m (high altitude [HA]). Symptoms of AMS were assessed using standard indexes derived from the Environmental Symptoms Questionnaire weighted toward cerebral (AMS-C) and respiratory (AMS-R) manifestations. Oxygen saturation was measured noninvasively by pulse oximetry at SL and HA. The mean (+/-SEM) uLTE4 levels (pg/mg creatinine) were 67.9 (+/-13.2) at SL; 82.3 (+/-5.5) at MA; and 134.8 (+/-19.4) at HA (p < 0.05 comparing HA with SL and MA). We conclude that uLTE4 levels increase shortly after exposure to HA even after staging for 4 days at MA. Although this study does not clearly demonstrate a relationship between uLTE4 levels and symptoms of AMS, it supports the hypothesis that leukotrienes may be involved in the pathophysiologic state of AMS.

Determination of LTE4 in human urine by liquid chromatography coupled with ionspray tandem mass spectrometry.

A sensitive and specific high-performance liquid chromatographic/ionspray tandem mass spectrometric (LC/ionspray MS/MS) method was developed and validated to quantitate leukotriene E4 (LTE4) in human urine. This method involves solid-phase extraction with Empore membrane disks to isolate LTE4 and its internal standard, LTE4-d3, from the urine stabilized with antioxidant and metal ion chelating agent. The reconstituted extracts were analyzed by LC/ionspray MS/MS in the selected reaction monitoring (SRM) mode. The assay has a lower level of quantitation (LOQ) of 50 pg ml-1 for LTE4 based on 5 ml aliquots of urine. The calibration graphs were linear from 50 pg ml-1 to 10 ng ml-1 for LTE4 extracted from urine. The inter- and intra-assay precision (RSD) and accuracy (DEV) did not exceed 11% and 8% at any level of the calibration standards and quality control (QC) samples, respectively. The recovery of LTE4 using the Empore disk solid-phase extraction technology was independent of LTE4 concentration in human urine. The overall extraction recovery for LTE4 was 72% (RSD = 2.14%).

Urinary leukotriene E 4 in the assessment of nocturnal asthma

Urinary leukotriene E4 (LTE4) is a marker of the body's production of cysteinyl LTs, important mediators of airway inflammation. The role of the latter in nocturnal asthma is a topic of increasing interest. This investigation was aimed at determining whether nighttime attacks are associated with increased release of LTs, expressed by urinary LTE4, and the relationship between the two phenomena. Three groups were studied: group A, seven control subjects; group B, nine asthmatic patients without nocturnal attacks; and group C, nine asthmatic patients with a comparable daytime FEV1 but who were experiencing nocturnal exacerbations (morning dips in peak expiratory flow greater than 20%). Urine was collected over 24 hours in three samples (9:00 AM to 3:00 PM; 3:00 PM to 9:00 PM; and 9:00 PM to 9:00 AM). LTE4 was measured by high-performance liquid chromatography and radioimmunoassay and expressed as nanograms per millimole of creatinine. No significant differences between urinary LTE4 were noticed within groups A and B. Conversely, in group C urinary LTE4 at night (geometric mean with 95% confidence interval; 35.16 with 28.77-42.85) was significantly higher than that of the other samples (respectively 23.12 with 17.78-30.06, p less than 0.05; and 25.18 with 21.03-30.13, p less than 0.02); it was also significantly higher than in all the samples of other groups. A significant (p less than 0.02) linear correlation was observed between morning dip in peak expiratory flow and the log urinary LTE4 in the nocturnal sample. These results indicate the role of LTs in nocturnal asthma and suggest that urinary LTE4 may be a useful marker of this condition.

Simplified method for measuring urinary leukotriene E 4

The conventional method for measuring urinary leukotriene E 4 (LTE4) is by reversed-phase high-performance liquid chromatography (RP-HPLC), followed by radioimmunoassay (RIA) or enzyme immunoassay (EIA). We measured urinary LTE4 levels by two methods, HPLC with EIA and EIA alone after initial crude extraction of urine using an octadecyl reversed-phase extraction cartridge (Sep-Pak). Ninety-three urine samples from normal subjects and patients with bronchial asthma and adult respiratory distress syndrome were tested. The results showed that urinary LTE4 levels measured by EIA significantly correlated with those measured by HPLC plus EIA in the three groups ( r=0.88, 0.85, 0.68). The absolute values of urinary LTE4 measured by EIA without HPLC purification were higher than by EIA with HPLC purification. This suggests that HPLC may not be necessary for routine urinary LTE4 quantitation in different clinical situations.

Persistent increase in plasma and urinary leukotrienes after acute asthma.

Leukotrienes may mediate bronchoconstriction in asthma. Cysteinyl leukotriene production rises in vivo after allergen challenge, but few reports describe leukotriene concentrations in clinical asthma or in children. Using high performance liquid chromatography/radioimmunoassay, plasma and urinary leukotrienes in asthmatic children (aged 5-10 years) were measured during an acute exacerbation (peak expiratory flow (PEF) < 65%, n = 10) and one month later (PEF 74-169%, n = 9), and in non-atopic normal children (aged 1.3-13.2 years). In the asthmatics, geometric mean (95% confidence interval) plasma leukotriene B4 (LTB4) was 746 pg/ml (398 to 1403) acutely and 1026 pg/ml (662 to 1593) in remission, compared with 369 pg/ml (167 to 728) in the normal children (n = 14). Plasma cysteinyl leukotrienes were low or undetectable, but urinary leukotriene E4 (LTE4) was higher in the asthmatics during an acute episode (210 pmol/mmol creatinine, 101 to 454) and at follow up (179 pmol/mmol, 110 to 293), compared with the normal children (98 pmol/mmol, 81 to 118, n = 41). This persistent increase in plasma LTB4 and urinary LTE4 concentrations one month after a severe asthmatic episode suggests leukotriene production is related to chronic inflammation rather than to acute bronchoconstriction.