Biomedical Engineering Reference
In-Depth Information
Figure 2
Neutrophil and endothelial cell adhesion molecules.
A. Direction of Migration
Neutrophils migrating within the lung encounter multiple chemoattractant
signals in complex spatial and temporal patterns as endothelial, epithelial
cells, and immune cells respond to infection or injury.
Most of our understanding about migration is from in vitro models
and it has become clear that neutrophils can migrate both up and down
chemical gradients, responding to one chemoattractant, migrating to its
concentration peak and then migrating up a novel, more distant chemoat-
tractant gradient, from endothelium to tissue. Once a concentration gradi-
ent has been traversed, neutrophils can ignore a high-concentration source
(due to receptor saturation, desensitization and
=
or receptor sequestration)
