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led to research which looked for less invasive methods of assessing the inflammatory
component of asthma and bronchoalveolar lavage and this led to the development of the
ability to induce sputum using nebulised hypertonic saline. These samples allowed increasing
measurement not only of the cellular component, but also of the proteins that formed the
asthmatic inflammation. These measurements could be done repeatedly so parameters were
followed longitudinally to determine what happened during acute exacerbations of asthma, in
response to treatment and over longer periods of time during chronic asthma. Studies were
also undertaken using blood and urine samples. In the main there has been a recognition that
the majority of asthma and other allergic diseases have an increased allergic inflammatory
profile with an eosiniphilic dominant pattern, raised levels of eosinophilic proteins @CP,
EPO, EDN and MBP), and cytokines (IL3, nA,n-5, rantes). While over the last decades this
was thought to be an imbalance between T lymphocyte classes, between the T helper type 2
(Ts2) and T helper type I (Tnl), (Colavita, Reinach et al. 2000; Holgate, Davies et al. 2000;
Busse and Irmanske 2001; Peters 2003), very recently it has been thought there may be
upregulation of both classes with a third type, the T lymphocyte regulatory cells playing a
pivotal role (Lazarus, Raby et al.2004; Goldman 2007). Certainly some asthma is known to
have a neutrophil dominant or neutrophil present pattern, with the markers more commonly
associated with infective conditions. This is seen more often in severe persistent asthma
(Wenzel, Szefler et al. 1997i Jatakanon, Uasuf et al. 1999), associated with a poor response to
treatment (McDougall and Helms 2006; Wenzel 2006), has been demonstrated in some acute
exacerbations (Martin, Cicutto et al. 1991; Fahy, Kim et al. 1995; Ordonez, Shaughnessy et
al. 2000), and in sudden fatal asthma (Sur, Crotty et al. 1993). While the eosinophils and
neutrophils themselves and the proteins they release have shown the best association with
asthma exacerbations and response to treatment - neither have been completely consistent. In
addition, obtaining the appropriate samples can be difficult.
So, while contributing enonnously to our understanding of asthma, the use of bronchoscopy,
biopsy and BAL, induced sputum, blood and urine testing all have their disadvantages,
particularly when assessing disease in children. The first three options remain invasive,
require anaesthesia in children and are associated with risks and side effects, especially in
children with respiratory disease, and therefore cannot be done frequently. They also require
specialised personnel in terms of theatre and bronchoscopy staff. Induced sputum results in
less satisfactory sample success in children than in adults, although successful samples can be
obtained in up to 757o of control children. It also can be associated with side effects, as
nebulised hypertonic saline is also used as an airway challenge. This test also requires
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