The thesis investigates reasons for a failure of neutrophils to clear pulmonary bacterial infection in cystic fibrosis (CF). Patients with CF experience bacterial colonization of the lungs associated with progressive lung injury and poor prognosis. Neutrophil responsiveness in vitro was determined in patients with CF at different clinical states, and compared to healthy subjects. Neutrophils from the patients were able to phagocytose and kill Pseudomonas aeruginosa effectively, but the presence of sputum sol reduced intracellular killing. Superoxide generation and elastase release in response to fMLP were shown to be reduced in neutrophils from patients with an exacerbation of respiratory symptoms. This was not observed when the cells were stimulated with PMA, which acts intracellularly, rather than through cell surface receptors. There was no difference in the down-regulation of cell surface L-selectin and up-regulation of CD11b in response to fMLP suggesting no alteration in number or function of the fMLP receptors. There was increased adherence to nylon columns by neutrophils from patients with CF. Infection resulted in a greater proportion of band neutrophils, and this correlated with the reduced superoxide generation and elastase release, although it was not possible to separate the band forms to prove this conclusively. Alterations in circulating lipid and fatty acid composition inpatients could potentially affect neutrophil membrane composition and fluidity and therefore signal processing or release of products. The reason for the observed reduced responsiveness appears to be multifactorial. Band cell number post receptor signalling and/or receptor desensitization may result in the observed reduced responsiveness, which returns towards healthy subject levels after treatment of an exacerbation, is likely to be the result of chronic infection.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:583381 |
| Date | January 2003 |
| Creators | Nixon, Lisette Sheena |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/54082/ |
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