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Friday, September 1st 2006

Too Cool

The Haversian Canal has linked to a company that does scientific CGI animations. This is the video of a white blood cell escaping a blood vessel.

During inflammation the johnny on the spot cells are macrophages. Cell damage and the macrophages release cytokines (like TNF and IL – 1) which do plenty – amongst their functions are making endothelial cells (which make up the blood vessels) “shrink,” to make the blood vessel leaky, and make those endothelial cells increase their expression of a group of molecules called selectins.

White blood cells (well enough a term for our purpsoses) traveling through the blood vessel express their own set of proteins called integrins (and some other glycoproteins). The selectins (expressed on the blood vessel) and the integrins (expressed on the white blood cell) fit like a lock and key. As the endothelial cells of the blood vessel start expressing more selectins, the white blood cell literally gets slowed down (as its integrins make and break connections with the selectins) and it starts “rolling” along the wall of the vessel, until finally it comes to a stop and is “adhesed” to the wall. It will then migrate outside the blood vessel so it can get to the site of inflammation (caused by infection or a foriegn body, etc.)

There was a bunch of other stuff I had to know for the general path test diapedesis was a part of – specific adhesion molecules, chemotactic factors, leukocyte activation – but the real idea is expressed above. Are some of those things examples of the overcrowding of the basic science years? Probably.

Pretty clever way your body works.