“Hang in there!” says the kitten dangling from a tree branch. Maybe this poster from my junior high-era bedroom should have had a white blood cell instead. While defending the body from infection, white blood cells have to anchor themselves to avoid being swept away from the constant blood flow around them. Today’s image is from a recent paper showing how this happens.
Leukocytes, or white blood cells, find their way to sites of infection in the body. Once there, leukocytes are subjected to the force of blood flow around them and must resist detachment from the inflamed tissue. Integrin cell adhesion proteins are important in stabilizing the anchors formed on leukocytes recruited to inflamed tissue. A recent paper shows that rapid actin polymerization at adhesion sites is triggered by the force of blood flow. In addition, Rullo and colleagues show that this actin polymerization is necessary for successful attachment. Image above shows human leukocytes on a surface coated with VCAM-1, a leukocyte adhesion molecule, and exposed to a fluid flow in the direction of the arrow. Arrowhead points to anchor points.
Rullo, J., Becker, H., Hyduk, S., Wong, J., Digby, G., Arora, P., Cano, A., Hartwig, J., McCulloch, C., & Cybulsky, M. (2012). Actin polymerization stabilizes 4 1 integrin anchors that mediate monocyte adhesion originally published in the Journal of Cell Biology, 197 (1), 115-129 DOI: 10.1083/jcb.201107140