The role that T cells play in IBD of Smad3−/− mice is not well defined, though others have observed increased CD4+ and CD8+ activated T cells in MLN (in addition to increased NK cells) and increased CD3+ cells and Granzyme B+ cells in the proximal colon following H. hepaticus infection in Smad3−/− mice [36]. This evidence concerns the gene SMAD3 and inflammatory bowel disease.