I. Antigen presentation in the intestine: new rules and regulations.

The recognition that immune responses in the intestine differ from those seen systemically has led to a search for novel pathways involved in mucosal immunoregulation. One cell type that has surfaced as a prime candidate for such a regulatory role is the intestinal epithelial cell. A number of laboratories have documented that intestinal epithelial cells sample luminal antigens and process and present these to primed T cells. However, several unique features have emerged, making their potential role as antigen-presenting cells a critical part of mucosal homeostasis.