CD4 and colitis: The differential induction of intestinal inflammation by the three mycobacteria might be due to a particular cell tropism of MAP to myeloid cells of the intestine i.e., a particular localization in the colon which could not be revealed by histology, Alternatively, MAP might induce a CD4+ T cell response to self-components or constituents of the enteric microbiota driving colitis in individuals suffering from an underlying mucosal disease.