dendritic cells
Summary
Dendritic cells are professional antigen-presenting cells (APCs) that serve as the primary link between innate and adaptive immunity. They capture antigens in peripheral tissues, migrate to lymphoid organs, and present processed antigens to T cells via MHC molecules to initiate immune responses.
Detail
Dendritic cells are derived from hematopoietic stem cells and exist in two main subsets: myeloid dendritic cells (conventional DCs) and plasmacytoid dendritic cells (pDCs). In their immature state, they reside in peripheral tissues as sentinels, using pattern recognition receptors (PRRs) like Toll-like receptors to detect pathogens. Upon antigen capture, they undergo maturation, upregulating co-stimulatory molecules (CD80, CD86) and MHC class I and II expression. They then migrate via lymphatics to secondary lymphoid organs where they present peptide-MHC complexes to naive T cells. This interaction, along with co-stimulatory signals and cytokines, determines whether T cells undergo activation, tolerance, or differentiation into specific effector subsets (Th1, Th2, Th17, Treg). Plasmacytoid DCs are specialized for producing large amounts of type I interferons in response to viral infections. Dysfunction of dendritic cells is implicated in autoimmune diseases, allergies, and cancer immune evasion.
Sources
- Janeway's Immunobiology
- Cellular and Molecular Immunology by Abbas
- First Aid for the USMLE Step 1
- Robbins Basic Pathology
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