1. ¹Dermatology Branch, Center for Cancer Research, National Cancer Institute, NIH, Bethesda, Maryland, USA
2. ²Present address: Department of Dermatology, Keio University, Tokyo, Japan

Correspondence: MC Udey, (udey@helix.nih.gov)

Received 25 July 2008; Accepted 31 July 2008; Published online 10 September 2008.

Abstract

Cutaneous accessory cells include dendritic cells (DCs) and macrophages. Heterogeneity, plasticity, and responsiveness to local environmental cues are hallmarks of both types of cells. Until recently, results of studies of cells that had been extracted from tissues or propagated in vitro provided the foundation for most conceptual frameworks. The availability of a variety of spontaneously occurring and genetically engineered mice has facilitated in vivo studies that have provided new insights into the developmental and functional aspects of DCs in skin and other tissues. In several instances, results of these in vivo studies have been very surprising. Existing paradigms have been modified or debunked, and new hypotheses have been generated. We can anticipate that detailed understanding of the biology of individual cutaneous accessory cells and their relationships with each other will continue to accumulate as these types of studies are actively pursued.