There is evidence of a direct link between persistent MICA expression, innate lymphocyte activation and Th1 cytokine production in a model of pathogenic Escherichia coli infection (32), suggesting that this host–bacteria interaction may be relevant to the pathogenesis of Crohn’s disease, as adherent E. coli strains have been isolated from inflammatory bowel disease (IBD) patients (33, 34). Here, MICA is linked to Crohn disease.