Inhibition of cell growth and induction of apoptosis on treatment of endothelial IL-8 in nude mice. The peritoneal space of nude mice (5 examined) were inoculated with K562 cells, and agents such as saline, endothelial IL-8 (IL-8 [E]), and monocyte-derived IL-8 (IL-8 [M]) were injected daily as described in Materials and Methods. (A) Morphology (Wright-Giemsa staining) and apoptotic cells (TUNEL assay) of intraperitoneal cells were collected. Arrows indicate the apoptotic cells. Original magnification × 160 and × 80. (B) Inhibition of cell growth of K562 cells by endothelial IL-8. Horizontal bars show the means. (C) The percentage of apoptotic cells was determined microscopically by counting more than 200 cells in situ on staining slides. Columns represent the means ± SD (bar) of three independent experiments. Statistical analysis was performed using the Student’s t-test.