PRESENTATION OF PEPTIDES AND PROTEINS BY INTESTINAL EPITHELIAL-CELLS

Murine intestinal epithelial cells (IEC) constitutively express major histocompatibility complex (MHC) class II molecules, which enable them to present foreign antigens to T cells in vitro. In this study we hav e compared the ability of freshly isolated IEC and spleen adherent cel ls to present both protein and peptide antigens to T cells in vitro. C onsistently IEC were unable to present protein but could readily prese nt immunogenic peptides in an MHC-dependent fashion to stimulate lymph okine release from T cells. Consistent with their inability to process protein antigens, IEC were also unable to present a synthetic peptide which requires intracellular processing, whereas spleen antigen-prese nting cells (APC) could readily present the same peptide. These findin gs indicate that IEC may lack the necessary intracellular machinery to process exogenous antigens but they raise the possibility that IEC ma y play an important immunological role in vivo by presenting processed peptides to T cells.