Submitted on February 19, 2009
Revised on May 6, 2009
Accepted on May 25, 2009
Airway hyperresponsiveness is associated with activated CD4+ T cells in the airways
Graeme R Zosky1*, Alexander N Larcombe1, Olivia J White1, Jennifer T Burchell1, Christophe von Garnier1, Patrick G. Holt2, Debra Jane Turner3, Matthew E Wikstrom1, Peter D. Sly3, and Philip A Stumbles1
1 University of Western Australia
2 University Western Australia
3 Telethon Institute for Child Health Research
* To whom correspondence should be addressed. E-mail: graemez{at}ichr.uwa.edu.au.
Abstract (244 words) Background: It is widely accepted that atopic asthma depends on an allergic response in the airway, yet the immune mechanisms that underlie the development of airway hyperresponsiveness (AHR) are poorly understood. Mouse models of asthma have been developed to study the pathobiology of this disease but there is considerable strain variation in the induction of allergic disease and AHR. The aim of this study was to compare the development of AHR in BALB/c, 129/Sv and C57BL/6 mice after sensitisation and challenge with ovalbumin (OVA). Methods: AHR to methacholine was measured using a modification of the forced oscillation technique in anaesthetised, tracheostomised mice order to distinguish between airway and parenchymal responses. Results: While all strains showed signs of allergic sensitisation, BALB/c was the only strain to develop AHR which was associated with the highest number of activated (CD69+) CD4+ T cells in the airway wall and the highest levels of circulating OVA-specific IgG1. AHR did not correlate with total or antigen-specific IgE. We assessed the relative contribution of CD4+ T cells and specific IgG1 to the development of AHR in BALB/c mice using adoptive transfer of OVA-specific CD4+ T cells from DO11.10 mice. AHR developed in these mice in a progressive fashion following multiple OVA challenges Conclusions: There was no evidence that antigen-specific antibody had a synergistic effect in this model, and we concluded that the number of antigen-specific T cells activated and recruited to the airway wall was crucial for development of AHR.
