An antigen reacting with Das-1 monoclonal antibody is ontogenically regulated in diverse organs including liver and indicates sharing of developmental mechanisms among cell lineages

The monoclonal antibody designated mAb Das-1, which was generated against a colon epithelial protein, reacts with the normal biliary epithelium and keratinocytes, which are among targets of tissue injury in ulcerative colitis. Moreover, mAb Das-1 reacts with abnormal cells in Barrett's esophagus and chronic cystitis profunda, as well as so-called 'oval cells' in the adult liver, which are considered oncogenic progenitor cells. To establish ontogenic regulation of mAb Das-1 reactivity, we studied 7- to 24- week-old human fetuses by immunohistochemistry. In liver, mAb Das-1 reactivity was further correlated with glycogen, dipeptidyl peptidase IV, glucose-6-phosphatase and γ-glutamyl transpeptidase expression. mAb Das-1 reacted with cells in organs arising from the pharyngeal cleft (thymus), primitive gut (oral cavity, pharynx, lung, esophagus, stomach, biliary tree, pancreas, liver, colon), ureteric bud (renal tubules, collecting duct), mesonephros (kidney, testis), mesoderm (muscle) and elsewhere (skin, adrenal cortex). In distinction from the adult liver, mAb Das-1 staining was more pronounced in hepatoblasts compared with biliary cells. In adult tissues, however, mAb Das-1 reactivity was restricted to the colon, biliary epithelium, keratinocytes, and ciliary body. These data indicated that the mAb Das-1 recognized epitopes in fetal cells of diverse ectodermal, mesodermal and endodermal origin, compatible with sharing of lineage mechanisms in tissues. Reactivation of mAb Das-1 staining in epithelial precancerous conditions, including carcinomas arising in these organs, is compatible with oncofetal regulation of the antigen, which will facilitate analysis of cell subpopulations during organ development, regeneration and oncogenesis. Copyright (C) 2000 S. Karger AG, Basel.