Neutrophils cascading their way to inflammation.

Neutrophils are pivotal effector cells of innate immunity. Their recruitment into peripheral tissues is indispensable for host defense. Given their destructive potential, neutrophil entry into tissue must be tightly regulated in vivo to avoid damage to the host. An array of chemically diverse chemoattractants is active on neutrophils and participates in recruitment. Neutrophil chemoattractants were thought redundant in the control of neutrophil recruitment into peripheral tissue, based on their often indistinguishable effects on neutrophils in vitro and their frequently overlapping patterns of expression at inflammatory sites in vivo. Recent data, however, suggest that neutrophil chemoattractants have unique functions in the recruitment of neutrophils into inflammatory sites in vivo, dictated by their distinct patterns of temporal and spatial expression.