<prompt> Increased permeability in acute inflammation is due to-HistamineIL-2TGFbFGF  <response>: Ans. a HistamineRef: Robbins 9thpg 74; 8thpg 47Increased vascular permeabilityFormation of endothelial gaps Immediate transient response is the most common mechanism Q for increased permeability.Most important immediate mediator responsible for Immediate transient response Q is histamine QOther immediate mediators: bradykinin, leukotriene, substance PSomewhat delayed mediators: TNF,IL-1,lFN-gOption b: IL2: IL-2 is known to activate T-cells, especially CD4 T-helper cells. Other minor function of IL2 are: IL2 can activate lipoxygenase pathway with release of lipoxygenase metabolites which play a role in pulmonary vascular permeability. Cytokines and Inflammation By Edward S. Kimball, pg215Option c and d: are mediators of chronic inflammation Here the answer is definitely histamine ?IL2 