Leukotriene B4: a mediator of vascular permeability

1 Intradermal injection of leukotriene B4 (LTB4) or prostaglandin E2 (PGE2), 1 to 100 ng per skin site produced little or no change in plasma exudation in the rabbit, guinea-pig and rat. 2 Intradermal injection of LTB4 or PGE2 together with bradykinin (500 ng) resulted in a significant potentiation of the plasma exudation produced by bradykinin alone in the rabbit and guinea-pig. 4 LTB4 (1 to 10 ng) had no effect on blood flow in the rabbit skin, in contrast to PGE2 which was a potent vasodilator in this species. 5 It is concluded that LTB4 is a mediator of vascular permeability and that this effect can only be observed in the presence of a vasodilator such as PGE2.