Editing Multiple sclerosis (section)

=== Blood-brain barrier ===
The blood-brain barrier (BBB) is a part of the [[capillary]] system that prevents the entry of T cells into the central nervous system.<!--<ref name="pmid11955556" /> --> It may become permeable to these types of cells secondary to an infection by a virus or bacteria.<!--<ref name="pmid11955556" /> --> After it repairs itself, typically once the infection has cleared, T cells may remain trapped inside the brain.<ref name="pmid119555563"/><ref>{{cite journal | vauthors = Huang X, Hussain B, Chang J | title = Peripheral inflammation and blood-brain barrier disruption: effects and mechanisms | journal = CNS Neuroscience & Therapeutics | volume = 27 | issue = 1 | pages = 36–47 | date = January 2021 | pmid = 33381913 | doi = 10.1111/cns.13569 | pmc = 7804893 }}</ref> [[Gadolinium]] cannot cross a normal BBB, so gadolinium-enhanced MRI is used to show BBB breakdowns.<ref name="pmid23088946">{{cite journal | vauthors = Ferré JC, Shiroishi MS, Law M | title = Advanced techniques using contrast media in neuroimaging | journal = Magnetic Resonance Imaging Clinics of North America | volume = 20 | issue = 4 | pages = 699–713 | date = November 2012 | pmid = 23088946 | pmc = 3479680 | doi = 10.1016/j.mric.2012.07.007 }}</ref>