ULTRASTRUCTURAL IMMUNOGOLD LOCALIZATION OF INTERLEUKIN-5 TO THE CRYSTALLOID CORE COMPARTMENT OF EOSINOPHIL SECONDARY GRANULES IN PATIENTS WITH ATOPIC ASTHMA

Bronchial biopsies from two patients with atopic asthma were analyzed by immunogold labeling to detect the ultrastructural location of inter leukin 5 (IL-5). In eosinophils, IL-5 was localized to the electron-de nse crystalloid core compartment of the secondary or specific eosinoph il granules. Other structures in the eosinophils were unlabeled. No IL -5 was detected in mast cells, Control sections incubated with an irre levant primary antibody were negative. This study demonstrates that pr e-formed IL-5 is stored within the major population of secondary granu les in human eosinophils.