Mark Davis, PhD, director of Stanford's Institute for Immunity, Transplantation and Infection, has spent his career exploring the mystery of the human immune system and how it mounts a response to the diversity of foreign antigens that assault us throughout our lives. In this video, Davis describes his unique approach to his work, and the progress his lab is making in developing a test for immunological health. For more information: http://www.stanford.edu/group/davislab/cgi-bin/drpl/