Dendritic cells (DCs) form a remarkable cellular network that shapes adaptive immune responses according to peripheral cues. After four decades of research, we now know that DCs arise from a hematopoietic lineage distinct from other leukocytes, establishing the DC system as a unique hematopoietic branch. Recent work has also established that tissue DCs consist of developmentally and functionally distinct subsets that differentially regulate T lymphocyte function. This review discusses major advances in our understanding of the regulation of DC lineage commitment, differentiation, diversification, and function in situ.

The dendritic cell lineage: ontogeny and function of dendritic cells and their subsets in the steady state and the inflamed setting.

Langerhans cells (LCs) are a specialized subset of dendritic cells (DCs) that populate the epidermal layer of the skin Langerin is a lectin that serves as a valuable marker for LCs in mice and humans In recent years, new mouse models have led to the identification of other langerin(+) DC subsets that are not present in the epidermis, including a subset of DCs that is found in most non-lymphoid tissues In this Review we describe new developments in the understanding of the biology of LCs and other langerin(+) DCs and discuss the challenges that remain in identifying the role of different DC subsets in tissue immunity

Origin, homeostasis and function of Langerhans cells and other langerin-expressing dendritic cells

Lineage promiscuity in hemopoietic differentiation and leukemia.

Iere partie: sarcoidose, histiocytose X. Le diagnostic, l'evaluation du stade, le traitement

Interstitial Lung Diseases of Unknown Cause: Disorders Characterized by Chronic Inflammation of the Lower Respiratory Tract

HUMAN cluster-of-differentiation 1 (CD1) is a family of cell surface glycoproteins of unknown function expressed on immature thymocytes, epidermal Langerhans cells and a subset of B lymphocytes1–3. Three homologous proteins, CD la, b and c, have been defined serologically4, and the CD1 gene locus on human chromosome 1 contains five potential CD1 genes5. Analysis of the predicted amino-acid sequences of CD1 molecules reveals a low but significant level of homology to major histocompatibility complex (MHC) class I and class II molecules5,6, and, like MHC class I molecules, CD1 molecules are associated non-covalently with (β2-microglobulin7. These structural similarities to known antigen-presenting molecules, together with the expression of CD1 on cells capable of antigen presentation, suggest a role for CD1 molecules in antigen recognition by T cells. Here we demonstrate the specific recognition of CDla by a CD4−CD8− αβ T-cell receptor (TCR) expressing cytolytic T lymphocyte (CTL) line and the specific recognition of CD1c by a CD4−CD8>minus; γδTCR CTL line. The interaction of GDI-specific CTLs with CD1+ target cells appeared to involve the CD3–TCR complex, and did not show evidence of MHC restriction. These results suggest that for a subset of T cells, GDI molecules serve a function analogous to that of MHG class I and II molecules.

Recognition of cluster of differentiation 1 antigens by human CD4 − CD8 >− cytolytic T lymphocyte

Reactivity of a monoclonal antibody with human Langerhans cells was demonstrated by a double-labeling immunofluorescence technique. Ia-bearing cells of the epidermis (Langerhans cells) were reactive with this antibody both in frozen sections and in cell suspensions prepared from human epidermis. This monoclonal antibody was unreactive with non-Ia-bearing epidermal cells and with peripheral blood B cells, T cells, and monocytes but did not bind to 70% of intrathymic lymphocytes. These observations further distinguish Langerhans cells from classical monocytes. Furthermore, this monoclonal antibody is a highly specific marker for the in vivo identification and in vitro isolation of Langerhans cells.

https://www.pnas.org/content/pnas/78/4/2541.full.pdf

Reactivity of Langerhans cells with hybridoma antibody

Induction of lymphocyte differentiation by epidermal cultures.

The skin and T-cell differentiation.

Reactivity of a monoclonal antibody with human Langerhans cells was demonstrated by a double-labeling immu- nofluorescence technique. Ia-bearing cells of the epidermis (Lan- gerhans cells) were reactive with this antibody both in frozen sec- tions and in cell suspensions prepared from human epidermis. This monoclonal antibody was unreactive with non-Ia-bearing ep- idermal cells and with peripheral blood B cells, T cells, and mono- cytes but did bind to 70% of intrathymic lymphocytes. These ob- servations further distinguish Langerhans cells from classical monocytes. Furthermore, this monoclonal antibody is a highly spe- cifilc marker for the in vivo identification and in vitro isolation of Langerhans cells.

Marian Rubenfeld

Papers

Reactivity of Langerhans cells with hybridoma antibody

Induction of lymphocyte differentiation by epidermal cultures.

The skin and T-cell differentiation.

Reactivity of Langerhans cells with hybridoma antibody (delayed hypersensitivity/monoclonal antibody/epidermis/antigen presentation/thymocyte antigen)