Localization of BPI in eosinophils after coincubation with STZ. Cells were prewarmed for 10 minutes at 37°C and activated with IL-5 at 0.1 nmol/l for 20 minutes before the addition of STZ and coincubation for 10 minutes. Ultrathin cryosections were incubated with anti-BPI and visualized by secondary gold-conjugated antibody. Area of an eosinophil showing a phagosome with a STZ containing BPI. Granules are seen fusing with the phagosome (arrowheads), whereas some intact granules (g) are seen close to the membrane of the phagosome. Bar = 400 nm.