Leukocyte transmigration across the
blood""?
brain barrier (BBB) is a multistep process that can be mediated by chemokines. These low-molecular-weight chemoattractant
proteins are secreted by
cells within the central nervous system (CNS) in response to injury or on activation. Leukocytes transmigrate toward this
chemokine gradient, crossing the BBB and gaining access to the CNS parenchyma. Depending on the
chemokine, the nature of the insult, and the type of
cell that transmigrates, the BBB integrity may be disrupted, leading to its increased permeability. Both the
inflammation resulting from leukocyte transmigration and BBB perturbations contribute to CNS
pathology. The mechanisms that mediate leukocyte transmigration and BBB disruption, as well as
tissue culture models that are used to study leukocyte trafficking, are the
focus of this review.