Differentiation-associated antimicrobial functions in human colon adenocarcinoma cell lines.

We report that the enterocytic cells of the HT-29 glc-/+ cell subpopulation strongly expressed two antimicrobial enzymes: the lysozyme and alpha1-antitrypsin. Moreover, we found that 20 to 30% of these cells expressed positive immunoreactivity using the mAbs directed against the gut porcine PR-39 and cecropin P1 antimicrobial peptides, but did not express immunreactivity against the human antimicrobial polymorphonucleated neutrophil-associated HNP 1-3 defensin and the Xenopus skin magainin. The HT-29 glc-/+ cell subpopulation develops bacteriolytic activity against the enterovirulent diffusely adhering C1845 Escherichia coli characterized by dramatic alterations of the bacterial cell, suggesting lysis, and bacterial death. In contrast, no expression of immunoreactivity against the antimicrobial peptides and no C1845 bacterial alteration were found in the cultured human embryonic undifferentiated INT407 cells and the colon adenocarcinoma T84 crypt cells. The development of the bacterial alteration and the expression of the antimicrobial components were examined as a function of the cell differentiation using the Caco-2 cell line which spontaneously differentiates in culture. We found that the bacterial alteration and the expression of the PR-39 immunoreactivity are differentiation-associated events. Altogether, our results suggest that in the intestine the enterocytes could develop antimicrobial defenses participating in the protection of the gut epithelium against enterovirulent microorganisms.