CIITA and gastrointestinal disease: This study aims to leverage canine intestinal organoids as a novel in vitro model to elucidate MHC class II expression dynamics and their implications in immune-mediated gastrointestinal diseases, bridging the gap between basic research and clinical application in canine health.<h4>Results</h4>Canine colonoids derived from healthy dogs showed significant expression of MHC class II and its promoter gene, CIITA, after IFN-γ treatment.