But the true significance of the discovery lies in its ramifications for the study and treatment of neurological diseases ranging from autism to Alzheimer’s disease to multiple sclerosis. Kipnis said researchers no longer need to ask questions such as, “How do we study the immune response of the brain?” or “Why do multiple sclerosis patients have immune system attacks?” “Now we can approach this mechanistically — because the brain is like every other tissue connected to the peripheral immune system through meningeal lymphatic vessels,” Kipnis said. “We believe that for every neurological disease that has an immune component to it, these vessels may play a major role.” Kevin Lee, who chairs the Department of Neuroscience, recalled his reaction the first time researchers in Kipnis’ lab shared their basic result with him.

“I just said one sentence: ‘They’ll have to rewrite the textbooks.’ There has never been a lymphatic system for the central nervous system, and it was very clear from that first singular observation — and they’ve done many studies since then to bolster the finding — that it will fundamentally change the way people look at the central nervous system’s relationship with the immune system,” Lee said.