Heterogeneity of eosinophils in chronic eosinophilic pneumonia.

It has previously been shown that patients with chronic eosinophilic pneumonia can be divided into 2 groups according to the chemotactic response of their eosinophils to 5 different eosinophil chemotactic factors (ECFs) and laboratory findings. In contrast, eosinophils obtained by bronchoalveolar lavage from both groups responded to all 5 ECFs. The correlation between the two groups and the expression of several antigens (VLA-4, CD69, ICAM-1 and CD11b) on eosinophils. The VLA-4 expression of group 1 eosinophils was higher than that of group 2 eosinophils. More interestingly, eosinophils that migrated towards ECF-PI9 expressed less CD69 than those that migrated towards other STO-2-derived ECF. The heterogeneous response of eosinophils to STO-2-derived ECFs suggests that the population of eosinophils is heterogeneous.