View - ResearchSpace@Auckland - The University of Auckland

2001). In paediatrics, BAL has also been used to compare inflammatory profiles with other
diseases that present with wheeze. An increase in eosinophil cell and proteins was seen in a
group of asthmatics compared to control and bronchiolitis groups (Kim, Chung et al. 2000;
Marguet, Dean et al.2C0l; Kim, Kim et al.2003; Kim, Kim et al. 2005). However, ILg levels
also correlated with the eosinophil level in the asthmatic group (Kim, Kim et al. 2003) and the
number of neutrophils appeared to reflect severity of asthma (Marguet, Dean et al. 2001). A
recent summary of these studies into airway inflammatory profiles in paediatric asthma has
been published (Warner 2003).
1.6.4 Inflammatory markers in induced sputum
1.6.4 (i) Studies in adult subjects
Non-isotonic ultrasonically produced aerosols were first used more than fifty years ago to
examine bronchial reactivity (Cheney and Butler lgT}).Currently, nebulised hypertonic saline
is used for three main reasons. Firstly, it can act as an airway challenge to evaluate hyper-
responsiveness. Secondly, it can be utilised as a treatment to aid expectoration of the
thickened sputum produced in some respiratory diseases, particularly CF @ng, Morton et al.
1996; Wark, McDonald et al. 2005; Donaldson, Bennett et al. 2006: Elkins, Robinson et al.
2006). Thirdly, it has been used to induce sputum for microbiological assessment (for
example in CF and TB) and/or for the harvest of cells and cytokines for research. The
technique consists of inhaling saline at 3-7Vo concentration generated by an ultrasonic
nebuliser, which is necessary to give a sufficient output for saline aerosol generation, for l0 to
30 minutes (Belda, Hussack et al. 2001). Patients or research subjects are requested to cough
and try to expectorate sputum into a container every 3-5 minutes (paggraro, Chanez et al.
2002). Dithiothreitol O.lVo is used to break down mucus suphylhydryl bonds and to disperse
cells. The samples are then centrifuged with slides made of the cellular component and
stained to identify cell viability, total cell counts, the percentage of squamous cells and
differential percentage or numbers of the other cell types. The sputum supernatant following a
cytospin preparation is then used for measurement of soluble mediators. The mechanism by
which hypertonic saline causes sputum production is uncertain, but thought to be a
combination of the osmotic movement of water into airways, the induction of cough and the
increased rate of mucociliary clearance (Umeno, McDonald et al. 1990; Holz, Kips et al.
2000; Paggiaro, Chanez et aL.2002). This technique was first described in the early 1990s to
obtain sputum samples from asthmatic and normal adult subjects (Fahy, Liu et al. lgg3). A
task force of European Respiratory Society members developed the ..Standardised
3l