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Allergen-Specific CD4+ T Cells in Human Asthma Have an Increased Capacity to Respond to Innate Type 2 Signals
Friday, March 4, 2016: 1:45 PM
Salon D (JW Marriott)
Morris F. Ling, MD, , , , , , , , ,
Rationale:  Asthma is a common chronic inflammatory disease characterized by eosinophilic airway inflammation and airway hyperresponsiveness.  We hypothesize that allergen-specific CD4+ T cells in the airway are critical drivers of allergic asthma.

Methods:  HLA-typed allergic asthmatic (AA, n=15) and allergic non-asthmatic (ANA, n=23) subjects were enrolled in a segmental allergen challenge (SAC) study.  The leukocyte composition of the bronchoalveolar lavage (BAL) fluid was analyzed in cytospin preparations.  BAL cytokine levels were measured using a Luminex assay.  Allergen-specific CD4+ T cells in the BAL were analyzed by flow cytometry after staining with dust mite (Der p 1) or cat (Fel d 1)-specific class II tetramers and antibodies to innate type 2 cytokine receptors (IL-33R and IL-25R) and other Th2 surface markers (CRTH2 and CCR4).

Results:  We found that both AA and ANA exhibited an increase in the number of allergen-specific CD4+ T cells in the BAL after SAC, but allergen-specific CD4+ T cells from AA exhibited increased IL-33R and CRTH2 expression compared with those from ANA.  IL-33R expression on allergen-specific CD4+ T cells correlated with eosinophilia, IL-4, IL-5, IL-13, IL-9, and CCL26 in the BAL, all of which were detected at higher levels in AA compared to ANA post-challenge.

Conclusions:  These results suggest that allergen-specific CD4+ T cells in the airway of AA compared to ANA subjects have an increased capacity to respond to innate type 2 signals (IL-33 and PGD2), which correlates with airway eosinophilia and Th2-associated inflammation.