Stumbled over this article and thought I'd share
Real-Time Observation Sheds New Light On Multiple Sclerosis
Scientists at the Max Planck Institute of Neurobiology, the University Medical Center Göttingen, using a two-photon microscope, succeeded in tracing the movements of aggressive T-cells. Outside the nervous system, the T- cells moved just as we would expect them to; most cells were floating along with the flow of the bloodstream. "Things got really exciting when we observed that the cells can actually crawl, a behavior so far unheard of for T-cells", Ingo Bartholomäus relates his observations. Here, "crawling" describes an active cell movement, usually against the flow of the bloodstream. The scientists watched T-cells as they took anything between a few minutes and several hours to crawl along the vessels' walls. At the end of such a search movement, the cells were either swept away again by the bloodstream or they managed to squeeze through the vascular wall. Although the scientists already knew that T-cells must make contact with phagocytes in order to become immune-activated, they were now able to observe these interactions right where they happened, i.e. at the blood-brain-barrier. And indeed, the T-cells did not launch their attack on the nervous system by releasing their inflammatory neurotransmitters until they had bonded with the phagocytes. As a result of the T-cells' activation, more and more T-cells passed through the vascular walls. "The activation of T-cells at the border to the nerve tissue appears to be a decisive signal for the invasion of the immune cells", concludes Alexander Flügel, supervisor of the study and director of the Department of Experimental and Clinical Neuroimmunology at the University Medical Center Göttingen and Head of the MS Hertie-Institute.