How do bad antibodies get into the brain, anyway?

In my post on anti-NMDA receptor encephalitis, I wrote that the blood-brain-barrier or BBB should prevent big and bulky antibodies from passing into the brain, but for reasons that are just beginning to be explored and understood, the BBB fails at its job. A reader, Bruce, asked , ” Is the ‘upshot’ of this that ‘we’ don’t really know how […]