Chemokine‐receptor expression on T cells in lung compartments of challenged asthmatic patients

Abstract

Background The interaction of chemokines with their receptors strongly influences the migration of leucocytes. Objective In order to assess the contribution of these molecules to the local recruitment of T cells in bronchial asthma, we analysed the expression of 14 chemokine receptors on lung‐derived T cells. Methods Chemokine‐receptor expression by T cells derived from the peripheral blood, the bronchoalveolar lavage fluid and the bronchial mucosa was analysed by flow cytometry and immunohistochemistry. Expression profiles in healthy and mildly asthmatic individuals were compared, the latter prior and after segmental allergen provocation. Results Compared with peripheral blood, alveolar T cells expressed significantly more CCR2, CCR5, CCR6, CXCR3 and CCR4. However, no differences were observed between healthy controls and unchallenged asthmatics. In patients developing significant inflammatory responses following specific allergen challenge, a marked increase in the percentage of CCR4⁺ and CCR7⁺, and reduced numbers of CXCR3‐bearing alveolar T cells were detected. Following specific allergen challenge, chemokine‐receptor expression profiles of T cells from the alveolar space and the mucosa or the submucosa were similar, excluding a particular subcompartmentalization of the chemokine/chemokine‐receptor system. Conclusion The expression of certain chemokine receptors by lung T cells suggests a contribution to the physiological recruitment of T cells to the lungs, both in healthy controls and unchallenged mild asthmatics. However, strong allergen‐induced airway responses were associated with a specific chemokine‐receptor profile, suggesting the involvement of certain chemokine receptors in the pathogenesis of allergic bronchial inflammation.