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.