Summary The inflammatory bowel diseases (IBD) are chronic, incurable conditions that contribute to significant morbidity and mortality in the Veteran population. Current therapies are effective long-term in only ~25% of patients with IBD, suggesting that as yet unknown immune cell subsets may be involved in the initial development and relapsing-remitting nature of IBD. We propose to elucidate T cell subsets that may play a role in the pathophysiology of IBD; this work may ultimately lead to new therapeutic targets for IBD.