Dr. Marrack has studied T cells, how they are created and how they operate for good or ill for more than 40 years, almost since the cells were discovered. The lab run jointly by Dr. Marrack and her husband, John Kappler, discovered the proteins that make up the T cell receptor, the proteins that allow T cells to recognize and respond to foreign invaders. Their lab also demonstrated one of the main processes that prevents T cells from attacking their own host, processes that prevent autoimmune diseases. Recently the lab has been working on vaccines, in attempts to understand how they work and how better vaccines can be created. Drs Marrack and Kappler have two children, three grandchildren, two dogs and a very mean cat.