Figure 1.

The role of chemical mediators in the acute inflammatory response. At the site of tissue injury or bacterial invasion, both exogenous and endogenous chemical mediators are liberated. Classic endogenous mediators such as prostaglandins and leukotrienes dilate vasculatures, enhance permeability of capillaries, increase blood flow, and stimulate the recruitment of neutrophils (PMNs) to form inflammatory exudate. Novel chemical mediators are produced in the evolution and resolution of the exudate that regulate tissue responses (see text for details). The black arrow denotes leukocyte traffic from venules and the dashed arrow denotes exogenous, i.e., bacterial components and chemoattractants.