Multivesicular late endosomes – MHC class II-enriched compartments in intestinal epithelial cells and origin of MHC class II-loaded exosomes

Background and aims: Intestinal epithelial cells (IEC) are suggested to present antigens to CD4+ T cells and were shown to release A33-positive, MHC class II/peptide-loaded exosomes with immunogenic properties. Dependent on inflammatory stimuli antigen presentation by IEC might be tolerogenic or pro-inflammatory. Here we investigated the subcellular compartments within IEC involved in antigen processing and class II peptide loading. Methods: Ovalbumin (OVA) was luminally injected into jejunal or ileal loops of TnfΔ(ARE) mice which spontaneously develop a Crohn's like ileitis, and C57/129SvEv controls. Specimens…