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
Increased permeability in acute inflammation is due to 
Select and explain. 
A. Histamine, B. IL-2, C. TGF-p, D. FGF
A: Histamine
Answer: A: Histamine 
Explanation: Formation of endothelial gaps in venules, i.e. immediate transient response is the most common mechanism causing increased vascular permeability in acute inflammation,
Mediators involved in this mechanism are

i. Immediate (more important): Histamine, bradykinin, leukotrienes, neuropeptide substance P.
ii. Somewhat delayed: IL-1, TNF, IFNγ