Moreover, epithelial cell-derived exosomes released into the mucosa may be taken up by mucosal DCs and transported to the MLNs, where their contents can effect the direction of mucosal adaptive immune responses, thereby directing the education of tolerogenic CD4+ T cell populations in conditions of homeostasis, as well as effector CD4+ T cells required to combat pathogenic microorganisms during microbial invasion or infection of the intestinal mucosa. The gene discussed is CD4; the disease is infection.