Ulrich von Andrian, M.D., Ph.D., is a Professor of Immunology at Harvard Medical School and a steering committee member of the Ragon Institute of Massachusetts General Hospital, MIT, and Harvard University. Throughout his career, he has worked to elucidate the multi-faceted fundamental processes that are essential for the body's defense against infections and for the pathogenesis, prevention, and treatment of inflammatory diseases. His work on leukocyte trafficking is now an integral part of every immunology textbook and has helped to lay a conceptual foundation for the development of drugs that block tissue-specific leukocyte trafficking to treat autoimmune diseases.