In vivo function of Langerhans cells and dermal dendritic cells

Abstract

In the past few years there has been an explosion in the characterization of skin-resident dendritic cells (DCs). This is largely because of the development of several lines of mice with genetic alterations that allow for selective targeting of many of these subsets. There are now considerable data derived from in vivo experiments using these mice. This review focuses on the relative contribution of murine skin-resident DCs in the generation of immune responses to epicutaneous application of ovalbumin and during contact hypersensitivity. We describe a model in which the two best-characterized skin-resident DCs, langerhans cells (LCs) and Langerin(+) dermal DCs (dDCs) have distinct functions: Langerin(+) dDCs initiate and LCs suppress T cell responses.

Figure 1. Participation of skin DC during contact hypersensitivity

Haptens (blue triangles) penetrate though the stratum corneum and into the epidermis and dermis soon after application (Day 0). They are acquired by LC (red cells in the epidermis), Langerin+ dDC (yellow cells in the dermis) and Langerin− dDC (green cells in the dermis). Approximately 1–2 days after application of hapten, dDC arrive in the skin draining lymph node. Langerin+ dermal DC cross-present antigen to CD8 T cells and initiate an adaptive response. Langerin+ and Langerin− dermal DC also likely present antigen to CD4 Th cells, though this has been less well explored. By day +3 LC arrive in the lymph node. After cognate interaction with CD4 T cells, LC suppress the development of effector CD4 and CD8 T cells though elaboration of IL-10 along with other unidentified factors.