Development and functional specialization of CD103+ dendritic cells.

CD103 (alpha(E)) integrin expression distinguishes a population of dendritic cells (DCs) that can be found in many if not all lymphoid and non-lymphoid organs. CD103(+) DCs display distinct functional activities. Migratory CD103(+) DCs derived from skin, lung, and intestine efficiently present exogenous antigens in their corresponding draining lymph nodes to specific CD8(+) T cells through a mechanism known as cross-presentation. On the T cells they prime, intestinal CD103(+) DCs can drive the induction of the chemokine receptor CCR9 and alpha(4)beta(7) integrin, both known as gut-homing receptors. CD103(+) DCs also contribute to control inflammatory responses and intestinal homeostasis by fostering the conversion of naive T cells into induced Foxp3(+) regulatory T cells, a mechanism that relies on transforming growth factor-beta and retinoic acid signaling. This review discusses recent findings that identify murine CD103(+) DCs as important regulators of the immune response.