Chemokine receptor expression on allergen-specific T cells in asthma and allergic bronchopulmonary aspergillosis.

Background: Allergic bronchopulmonary aspergillosis (ABPA) is a rare variant of severe asthma resulting from hypersensitivity to Aspergillus fumigatus (Asp f) present in the airways. Aims of the study: We analyzed the expression of a panel of six chemokine receptors (CCR3, CCR4, CCR8, CCR5, CXCR3 and CXCR4) on total blood CD4⁺ T cells and Asp f-specific-T cells in ABPA patients. We hypothesized that chemokine receptor pattern on T cells differs between ABPA patients, non-ABPA allergic asthmatics sensitized to Dermatophagoides pteronyssinus (Der p) or Phleum pratense (Phl p) and healthy controls. Methods: We used the fluorescent dye PKH26, a membrane bound marker, to identify accumulated proliferating (cell-sorted PKH26^low) CD4⁺ T cells in response to allergens (Asp f, Der p, Phl p) or recall antigens (PPD and TT). Chemokine receptor expression was analyzed by flow cytometry on proliferating CD3⁺ CD4⁺ PKH26^low cells. Results: Stimulation of CD4⁺ T cells with the relevant allergen resulted in different patterns of chemokine receptor expression in ABPA and non-ABPA allergic asthmatics. Upon Asp f exposure, proliferating CD4⁺ T cells from ABPA patients down-regulated the expression of CCR4 and CXCR3 while CCR4 and CXCR3 were up-regulated in allergen-specific T cells from non-ABPA allergic asthmatics. Considering each group of patients, the pattern of chemokine receptors expressed on proliferating allergen-specific CD4⁺ T cells was similar to that expressed by recall antigen-specific T cells. Conclusions: The down-regulation of CCR4 and CXCR3 after allergen exposure in Asp f-specific T cells seems to be a characteristic feature of ABPA patients and requires further evaluation. [ABSTRACT FROM AUTHOR]