Tom MacDonald is Professor of Immunology and Director of the Division of Infection, Inflammation and Repair at the University of Southampton. He has spent his career studying the role of intestinal T cells in health and disease, and has made major contributions to our understanding of the mucosal immune system. He was one of the first people to appreciate the importance of lamina propria T cells and their potential for secreting specific profiles of cytokines that drive the inflammatory response in inflammatory bowel disease. Subsequently Tom MacDonald was again at the forefront of new insights when he reported the important link between lymphocytes, cytokines and matrix degradation.