Cytochrome c is released from the mitochondria during spontaneous and STS-induced eosinophil apoptosis.
Immunocytochemistry was performed, as described in “Materials and methods,” on fixed cytospins of freshly isolated eosinophils (A) or eosinophils cultured in the absence (B) or presence of IL-5 (10−10 M) for 6 hours (C) or STS (10−5 M) for 2 hours (D). Images were captured by confocal microscopy at × 100 magnification under oil immersion. Cytochrome c was detected using a monoclonal antibody 6H2.B4 and the mitochondria and nuclei stained with Mitotracker CMXRos and Hoechst 33258, respectively. Colocalization (yellow) of cytochrome c (green) and mitochondria (red) was observed in single sections. Eosinophils exhibiting evidence of cytochrome c release are indicated (arrows in panels B and D). Culturing in the absence of IL-5 for 6 hours and treatment with STS for 2 hours induced cytochromec release from the mitochondria. Bar represents 10 μm. Results are representative of experiments performed on 4 separate donors.
