Expression of CCR8 is increased in asthma.

BACKGROUND

Chemokines and their receptors could play key roles in the recruitment of T cells to the asthmatic lung. CCR8 is preferentially expressed on T-helper type 2 cells, and is thought to play a role in the pathogenesis of human asthma.

OBJECTIVE

Determine the expression of CCR8 on T cells in blood, bronchoalveolar lavage (BAL) and bronchial mucosa from asthmatics and normal subjects.

METHODS

CCR8 expression in blood and BAL from asthma and normal subjects was studied using flow cytometry. CCR8 expression on IFN-gamma+ and IL-4+/IL-13+ blood and BAL T cells was studied following stimulation with Phorbol-Myristate-Acetate and Calcium Ionophore. Paraffin-embedded bronchial biopsies were used to study CCR8 in bronchial epithelium.

RESULTS

The percentage of CD3+ cells expressing CCR8 in the blood was higher in asthmatics (4.7+/-0.4%) compared with normal subjects (3.0+/-0.4%; P<0.01). There was an approximately sixfold enrichment of CCR8 on IL-4+/IL-13+ cells compared with IFN-gamma+ T cells (P<0.001) in both asthmatic and normal subjects in both blood and BAL. Significantly more BAL T cells expressed CCR8 in asthmatic (8.6+/-0.8%) compared with normal subjects (3.9+/-0.7%) (P<0.01). In paired blood-BAL samples from asthmatics, significantly more CCR8+CD3+ T cells were present in BAL (9.0+/-0.9%) than in blood (5.6+/-0.9%; P<0.05). There were more CCR8-positive cells in bronchial biopsies from asthmatic (93+/-11 cells/mm2) compared with normal subjects (30+/-16 cells/mm2) (P<0.05). The ligand CCL1 was increased in the BAL of asthmatics compared with normal subjects (35+/-6 vs. 12.9+/-7 pg/mL; P<0.05).

CONCLUSION

There may be a role for CCR8 in the recruitment of T cells to the lung in asthmatics.