IL-8 mediates 15(S)-HETE–induced angiogenesis. (A) Quiescent HRMVECs were treated with and without 15(S)-HETE (0.1 μM) for the indicated time periods, and either RNA was isolated and analyzed for IL-8 mRNA levels by RT-PCR, or medium was collected and analyzed for IL-8 release by ELISA. (B,C) Quiescent HRMVECs were treated with and without neutralizing anti–IL-8 antibodies (3 μg/mL) for 30 minutes at 37°C, followed by washing with medium 131. The cells were then subjected to 0.1 μM 15(S)-HETE–induced migration (B) or tube formation (C) in the presence and absence of 3 μg/mL neutralizing anti–IL-8 antibodies. (D) C57BL/6 mice were injected subcutaneously with 0.5 mL of Matrigel premixed with vehicle or 5 μM 15(S)-HETE with and without 3 μg/mL neutralizing anti–IL-8 antibodies. One week later, the animals were killed and the Matrigel plugs were harvested from underneath the skin, and cryosections were either made and immunostained for CD31 using anti-CD31 antibodies or analyzed for hemoglobin content using Drabkin reagent. Wherever appropriate, preimmune serum was added to the control groups. The bar graphs in panels A through D represent the mean ± SD values of 3 independent experiments or 6 plugs from 6 animals. *P < .01 versus control; **P < .01 versus 15(S)-HETE.