Pediatric ulcerative colitis patients had higher levels of activated HLA.DR+ β1-integrin+ CD8+ T cells in the periphery and that correlated positively to systemic and mucosal inflammation biomarkers. Pediatric Crohn ́s disease patients showed equal levels of activated HLA.DR+ β1-integrin+ CD8+ T cells to controls, but an increase on the CD23+ B cell population. Here, FCER2 is linked to ulcerative colitis.