Murine Epidermal Langerhans Cells as A Model to Study Tissue Dendritic Cells
Dendritic cells (DC) form a system of widely distributed antigen presenting cells that seems essential to initiate immmune responses 1. The study of epidermal Langerhans cells (LC) was important to unravel how the individual components of this system interact 2. It became evident that DC accomplish their task as “nature’s adjuvant” in the afferent limb of the immune system in three discrete steps: immature DC are located in peripheral non-lymphoid tissues (“tissue DC”) and are specialized to capture and process antigen (“sentinel function”). Following rapid downregulation of their antigen processing capacity they begin to develop into mature DC by acquiring the capacity to stimulate resting T cells. These cells then migrate as “veiled cells” via afferent lymph (or blood) to the T areas of the lymph node (or spleen) (“migratory function”), where they appear as “lymphoid DC”, select antigen-specific T cells from the circulating pool and stimulate them (“sensitizing function”). Here we will review the studies of murine LC that have helped to establish this concept of DC function. We will also outline recent data about the modulation of LC function by cytokines, the evidence that DC and LC constitute a distinct hematopoietic lineage, and hints for a novel role of LC as regulators of keratinocyte proliferation.
KeywordsMature Dendritic Cell Dendritic Cell Function Stem Cell Inhibitor Lymphoid Dendritic Cell Cytokine Gene Expression Profile
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