The usefulness of competitive PCR: airway gene expression of IL-5, IL-4, IL-4delta2, IL-2, and IFNgamma in asthma.
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 housekeeping 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)gamma, IL-2, IL-5, IL-4 and its receptor antagonist encoding splicing variant IL-4delta2 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. IFNgamma, IL-4, and IL-4delta2 mRNA levels did not differ between any groups and were not affected by steroid use. IL-4 and IL-4delta2 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.
Glare
E M
EM
Department of Respiratory Medicine, Alfred Hospital and Monash University Medical School, Melbourne, Australia.
Divjak
M
M
Bailey
M J
MJ
Walters
E H
EH
D000328:Adult; D000368:Aged; D001249:Asthma / Q000378:metabolism*; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D003430:Cross-Sectional Studies; D005260:Female; D015870:Gene Expression; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism*; D007378:Interleukins / Q000378:metabolism*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D007378:Interleukins; D012333:RNA, Messenger; D007371:Interferon-gamma