View - ResearchSpace@Auckland - The University of Auckland

older children, particularly those > 12 years of age (Norzila, Fakes et al. 2000; Covar, Spahn
et aL.2004; Rytila, Pelkonen et aL.2004; kx, Payne et al. 2005). In the CAMp study, 90 out
of 117 children (75Vo) with mild to moderate asthma across eight centres provided an
adequate sputum sample for analysis (Covar, Spahn et al.20O4). The total cell counts were
the only similar result when induced sputum samples were examined on two separate days,
two weeks apart in the same 37 subjects (Thomas, Yates et al. lggg). Considerable
heterogeneity was also documented, particularly in eosinophils, in samples from over 250
adult asthmatics and normal subjects (Green, Brightling et a\.2002). Some of the variability
seen between groups may be due to differing techniques. A range of 0.9 to lT%o concentration
of saline has been used, with the measurement being of either the whole expectorated sample
or a sample separated from saliva or by picking out mucus plugs. The plugs were thought to
provide more cells with better cell viability (Gershman, Wong et al. 1996; pjzzichini,
Pizzichini et al. 1996; Spanevello, Beghe et al. 1998) while selected sputum had higher
concentrations of soluble markers such as ECP (Gershman, Wong et al. 1996: Spanevello,
Beghe et al. 1998). Using 0-5 minutes of hypertonic saline gave more neutrophils, while using
a longer period of 10-15 minutes gave higher concentrations of eosinophils ,nA and,Il5 with
lymphocytes, macrophages and epithelial cells remaining unchanged (Taha, Hamid et al.
2004)- A comparison of induced and spontaneous sputum samples showed an increased
number and more viable cells in the former process (Pizzichini ,Pizzichiniet al. 1996).
In addition, the induction procedure itself may alter findings. Consecutive sputum samples
during one sputum induction displayed an increasing neutrophil gradient (Holz, Jorres et al.
1998; Nightingale, Rogers et al. 1998; Richter, Holz et al. 1999 Belda, Hussack et al. 2001)
which occurred within six hours and lasted for 24 (Holz, Jorres et al. 1998; Nightingale,
Rogers et al. 1998) with decreasing mucin and increasing concentrations of surfactant
(Gershman, Liu et al. 1999). This effect was observed with both high and low output
nebulisers (Berlyne, Irmiere et al. 1998). Repeated sputum induction over days also resulted
in increased neutrophils with decreasing macrophage and eosinophil numbers (Belcher,
Murdoch et al. 1988; Holz, Richter et al. 1998) and the effect of hypertonic saline on nasal
mucosa resulted in increased histamine and leukotriene release (Silber, Proud et al. lggg).
The exact cause of this inflammatory response is unknown but the additional fluid,
hypertonicity, frequent coughing, or possibly bacterial contamination could all be
contributory (Holz, Richter et al. 1998; Nightingale, Rogers et al. 1998; Sacco, Fregonese et
al. 2000).
37