<prompt> Increased permeability in acute inflammation is due toHistamineIL-2TGF-pFGF  <response>: 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 arei. Immediate more important: Histamine, bradykinin, leukotrienes, neuropeptide substance P.ii. Somewhat delayed: IL-1, TNF, IFNγ 