Dr. Jonathan Kipnis is the BJC Investigator and Alan A. and Edith L. Wolff Distinguished Professor of Pathology and Immunology at Washington University in St. Louis. His lab investigates the complex interactions between the immune and nervous systems. He talks about immune activity and surveillance in the brain, and how T cell subsets affect brain function and behavior. He also discusses the brain's immune reservoir and his lab's work on cerebrospinal fluid-regulated immune cell mobilization.