IL15 and inflammatory bowel disease: The unbalance of the two kinds of memory T cell created a beneficial environment to form the unbalance between the CD4+ T cell and CD8+ T cell which induced highly-expressed proinflammatory factors (e.g. IL-2, IL-7, IL-12, and IL-15) and lower-level anti-inflammatory factors (e.g. IL-10) and then led to inflammatory colonic injury and ulceration, which finally caused spontaneous recurrent seizures of IBD.