If you put your questions into the search box above, or into the search archives box which is above all the latest posts, you will find the technical information on this drug and many many of the forum posts on the topic. Just type "what is Tysabri" or what ever you want to know and if its already been talked about it will come up :-)
Natalizumab is a humanized monoclonal antibody. In MS, it prevents immune cells (T cells) from attaching to the the endothelium in the vessels of the brain and passing outside the vessel and breaching the blood brain barrier.
There is a pretty good explanation on Wikipedia.
Wikipedia contributors. "Natalizumab." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 30 Jun. 2011. Web. 1 Jul. 2011.
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