Chemotactic heterogeneity of eosinophils in idiopathic pulmonary eosinophilia

Heterogeneity in the chemotactic response of eosinophils to 5 T cell line eosinophilic chemotactic factors (ECFs) was assessed in 5 patients with idiopathic pulmonary eosinophilia. Eosinophils from 2 patients responded to all 5 ECFs (group 1), whereas eosinophils from the other 3 patients responded to ECF-PI 5, PI 6, PI 7 and PI 8 but failed to respond to ECF-PI 9 (group 2). It was further found that group 1 showed an elevated level of lactate dehydrogenase and a positive tuberculin reaction, whereas group 2 showed neither. The effects of steroid therapy on the chemotactic responses of eosinophils were also examined. In group 1, the chemotactic response of eosinophils to ECF-PI 9 was significantly diminished after therapy; in contrast it was elevated in group 2. This change was accompanied by resolution of both clinical symptoms and pulmonary infiltration of eosinophils. These findings suggest that pulmonary eosinophilia can be divided into two types on the basis of eosinophil chemotactic response and laboratory findings. The heterogeneous responses of eosinophils to ECFs may provide a useful marker for classification of pulmonary eosinophilia and evaluation of therapy.