Dr. Vijay Kuchroo is the Samuel L. Wasserstrom Professor of Neurology at Harvard Medical School. His major research interests include the role of co-stimulation in autoimmune diseases, as well as cell surface molecules and regulatory factors that regulate the induction of T cell tolerance and dysfunction. He talks about the conditions necessary to differentiate Th17 cells and their role in autoimmunity. He also discusses his group's discovery of Tim-3, an inhibitor receptor on T cells which is now being exploited for cancer immunotherapy.