Background - Asthma has been described as an eosinophilic bronchitis driven by interleukin(IL)-4 and IL-5. The quantification of cytokine mRNA levels in airway samples has been confounded by house-keeping gene expression which differs between and within asthmatics and controls. Methods - The usefulness of competitive reverse transcriptase-polymerase chain reaction (RT-PCR) that is independent of housekeeping gene expression for quantitating the mRNA for interferon (IFN)γ, IL-2, IL-5, IL-4 and its receptor antagonist encoding splicing variant IL-4δ2 was determined in a cross sectional study of 45 normal control subjects and 111 with asthma. Results - Atopic controls and atopic asthmatic subjects expressed more IL-5 than non-atopic controls (p<0.02) in bronchoalveolar lavage (BAL) cells, but not in biopsy specimens. IL-5 mRNA expression in BAL cells from asthmatic subjects using inhaled corticosteroids (ICS) was significantly lower than those not receiving ICS (p=0.04). IL-2 mRNA levels differed with steroid use in biopsy specimens but not in BAL cells. IFNγ, IL-4, and IL-4δ2 mRNA levels did not differ between any groups and were not affected by steroid use. IL-4 and IL-4δ2 mRNA levels were positively correlated (p<0.0001), suggesting coordinated transcription. Conclusions - While the signal differentiation of competitive PCR in asthma may rival that of in situ hybridisation and immunohistochemistry, the method is expensive and wasteful of material.

Item Type:	Refereed Article
Research Division:	Biomedical and Clinical Sciences
Research Group:	Cardiovascular medicine and haematology
Research Field:	Respiratory diseases
Objective Division:	Health
Objective Group:	Clinical health
Objective Field:	Clinical health not elsewhere classified
UTAS Author:	Walters, EH (Professor Haydn Walters)
ID Code:	21825
Year Published:	2001
Web of Science® Times Cited:	13
Deposited By:	Medicine
Deposited On:	2001-08-01
Last Modified:	2002-07-04
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