A 63-year-old homeless man is brought to the emergency department 1 hour after police found him unresponsive. His respirations are 30/min. Crackles are heard over the left upper and the entire right l

A 63-year-old homeless man is brought to the emergency department 1 hour after police found him unresponsive. His respirations are 30/min. Crackles are heard over the left upper and the entire right lung fields. Despite appropriate lifesaving measures, he dies. A photomicrograph of a section of the right lung obtained at autopsy is shown. Which of the following mediators is the most likely cause of the position of the cell indicated by the arrow?