CD80 and digestive system neoplasm: The prevalence of CD80+ epithelial foci in correspondence of LGD or HGD, as opposed to the homogeneously distributed CD80+ lamina propria mononucleated cells in the presence of normal or dysplastic epithelium, further suggests that epithelial cells, in addition to professional APCs, are involved in the cross-talk with T lymphocytes in colon carcinogenesis.