Surface antigens on eosinophils in bronchial asthma and eosinophilic pneumonia.

Surface antigens on peripheral blood eosinophils from 23 patients with bronchial asthma, 6 with eosinophilic pneumonia and 8 controls were examined using a new direct method. Peripheral blood eosinophils in bronchial asthma and eosinophilic pneumonia showed higher complexity and/or granularity than those from controls. The percentage expression of HLA DR, CD4 and CD45RO on peripheral blood eosinophils from patients with bronchial asthma were increased compared with those from patients with eosinophilic pneumonia and from the controls. These results suggest that peripheral blood eosinophils in bronchial asthma may play a role in immunoregulation via the expression of human leukocyte antigens, such as HLA-DR, CD4 and CD45RO, that interact with lymphocytes, and may function as antigen-presenting cells. Furthermore this study suggests that there may be different phenotypes of eosinophils with differing surface antigens and intercellular reactions between eosinophils and lymphocytes.