Although leukotrienes (LTs) are implicated in the pathogenesis of asthma, it is still unclear which types of cells are of primary importance in their formation in asthmatic lungs. To elucidate the mechanism for the increased LT formation in asthma, we investigated the pulmonary cellular infiltration and LT synthesis by dispersed lung cells from BN rats following allergen challenge. / To enable us to do these studies we have developed improved HPLC methods for the analysis of complex mixtures of eicosanoids in biological samples using binary gradients containing trifluoroacetic acid. Samples containing PGB$ sb2$ (the internal standard), cysteinyl-LTs, LTB$ sb4,$ hydroxyeicosatetraenoic acids (HETEs) and the cyclooxygenase product 12-hydroxy-5,8,10-heptadecatrienoic acid (12-HHTrE) can be analyzed in as little as 20 min. Mixtures which also contain more polar eicosanoids such as lipoxins and omega-oxidation products of LTB$ sb4$ can be analyzed in 40 min. / Ovalbumin (OVA) challenge of sensitized BN rats resulted in a significant influx of neutrophils into the lungs and a significant increase in the synthesis of 5-lipoxygenase products, in particular LTB$ sb4$, by lung cells 6 h after challenge. However, there was little change in the production of cysteinyl-LTs compared with saline challenge. There was a significant eosinophilic infiltration in the lungs 24 h after OVA challenge, but cysteinyl-LT production by lung cells was unaltered at this time suggesting that eosinophils from BN rats are unlikely to be a major site for the formation of these compounds. This was confirmed in experiments with partially purified eosinophils obtained from Sephadex-treated rats. In contrast, cysteinyl-LTs were synthesized in appreciable amounts by alveolar macrophages from BN rats. Administration of rabbit anti-rat PMNL serum abolished the influx of neutrophils into the lungs and appeared to reduce the LTB$ sb4$ synthesis by lung cells. There was a positive correlation between the numbers of neutrophils in the lung and LTB$ sb4$ production by lung cells. In contrast, macrophages were positively associated with cysteinyl-LT production. Exogenous LTB$ sb4$ and 5-oxo-ETE induced infiltration of eosinophils into the lungs and therefore may be responsible for the late phase eosinophilic infiltration in BN rat lungs following allergen challenge.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.34484 |
| Date | January 1996 |
| Creators | Yu, Wengui. |
| Contributors | Powell, William S. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001549337, proquestno: NQ30424, Theses scanned by UMI/ProQuest. |
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