Langerhans cells and more: langerin‐expressing dendritic cell subsets in the skin

Abstract

SummaryLangerhans cells (LCs) are antigen-presenting dendritic cells (DCs) that reside in epithelia. The best studied example is the LC of the epidermis. By electron microscopy, their identifying feature is the unique rod-or tennis racket-shaped Birbeck granule. The phenotypic hallmark is their expression of the C-type lectin receptor langerin/CD207. Langerin, however, is also expressed on a recently discovered population of DC in the dermis and other tissues of the body. These 'dermal langerin + dendritic cells' are unrelated to LCs. The complex field of langerin-negative dermal DCs is not dealt with here. In this article, we briefly review the history, ontogeny, and homeostasis of LCs. More emphasis is laid on the discussion of functional properties in vivo. Novel models using genetically engineered mice are contributing tremendously to our understanding of the role of LCs in eliciting adaptive immune responses against pathogens or tumors and in inducing and maintaining tolerance against self antigens and innocuous substances in vivo. Also, innate effector functions are increasingly being recognized. Current activities in this area are reviewed, and possibilities for future exploitation of LC in medicine, e.g. for the improvement of vaccines, are contemplated.

From skin dendritic cells to a simplified classification of human and mouse dendritic cell subsets

“…They include (i) a side-by-side comparison of the phenotypes, gene expression programs and proteomes [44,45] [1,2]. pDC detect RNA and DNA from viruses and RNA/DNA/ immunocomplexes through two endosomal sensors, TLR7 and TLR9, respectively, both of which induce secretion of IFN-I through the MyD88-IRF7 signaling pathway [3][4][5].…”

“…The functional specialization existing among skin DC subsets is specified in the boxes. All skin DC subsets are capable of inducing delayed type hypersensitivity reactions provided that they have been exposed to the inducing agent [1,5,56]. In addition, CLN contain LT-DC that correspond to the CD8a 1 , the CD11b 1 and the pDC subsets.…”

“…After switching from a sessile to a mobile state, LC carry these antigens to the LN that drain cutaneous territories (CLN) [1]. Recent studies, however, demonstrated the existence of a complex network of dermal DC (DDC) and also suggested that LC might play an indirect role in T-cell priming, i.e.…”

Fine-Needle Aspiration Biopsy of the Lymph Node: A Novel Tool for the Monitoring of Immune Responses after Skin Antigen Delivery

“…Intradermal administration of Ags is used both to induce responses (as in vaccination) and to monitor immune memory (as in delayed type hypersensitivity tests) as well as in attempts to induce Ag specific tolerance (1,2). The immense potential of the dermal route has been underlined in recent years by the discovery that the epidermis and upper dermis not only have a very high density and wide variety of APCs (3,4) but also a large previously underappreciated reservoir of resident T cells, twice as large as the blood pool (5). This reservoir is polyclonal and in contrast to the blood or lymph node (LN) contains almost exclusively T cells of memory phenotype (6).…”

Langerhans Cell Histiocytosis: Diagnosis on Thyroid Aspirate and Review of the Literature

“…This fact is important as recent studies have revealed the existence of subsets of Langerin (? ), non-Langerhans dendritic cells, especially in the dermis [4,5]. Langerhans cell histiocytes less often express maturation associated antigens such as CD83 compared to other types of myeloid derived dendritic cells [6,7].…”