This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Which of the following is a chemokine? 
Select and explain. 
A. Leukotriene A4, B. IL-8, C. C5, D. C3
B: IL-8
Answer: B: IL-8 
Explanation: Their name is derived from their ability to induce directed chemotaxis in nearby responsive cells; they are chemotactic cytokines. Interleukin-8 (IL-8) is a chemokine produced by macrophages and other cell types such as epithelial cells. It is also synthesized by endothelial cells, which store IL-8 in their storage vesicles, the Weibel-Palade bodies.