[Expression of activation antigen, CD69, on human local eosinophils]

The activation antigen, CD69, has been shown to be expressed on activated lymphocytes. CD69 has also been shown to be associated with the signal transduction process. Recently, we demonstrated the expression of CD69 on lung eosinophils obtained from the bronchoalveolar lavage fluid of patients with eosinophilic pneumonia. In this study, we performed flowcytometric analysis of CD69 expression on eosinophils obtained from the bronchoalveolar lavage fluid, pleural effusion or peripheral blood of various patients. Whatever the disease, local eosinophils expressed significant levels of CD69, whereas most peripheral blood eosinophils did not express CD69. These findings suggest that CD69 is a marker for local eosinophils and that local eosinophils may differ functionally from peripheral blood eosinophils.