Localization of BPI in eosinophils. Cryosections of eosinophils labeled to detect BPI. Labeling of the core-containing specific granules of eosinophils was heterogeneous. The top of the micrograph shows an eosinophil with labeled granules (large arrows); however, the labeling was less intense than in the neutrophil at the bottom. Some labeling (small arrows) was also observed on the surface membrane of the eosinophil (insert). The nucleus (n) was unlabeled. Bars = 200 nm.