Mucosal Immunity and Inflammation III. The mucosal antigen barrier: cross talk with mucosal cytokines

We have known for many years that mucosal responses to antigens are regulat ed by immune cells and their molecular signals. More recently, it has becom e clear that epithelial cells also synthesize and secrete chemokines and cy tokines. A sophisticated system of bidirectional cytokine signals is respon sible for immune activation in the case of enteropathogens vs. immune suppr ession to food and commensal microbial antigens. A key factor in determinin g antigen handling is the route taken by antigens across the epithelial bar rier. Cytokines and other mucosal messenger molecules play a critical role in the regulation of transepithelial antigen transport.