Dendritic cells are bone marrow derived cell which play a critical function in inducing the immune response and similar to the dendrites of the nerve cells in appearance. Dendritic cells are act as antigen presenting cells (APC) and present antigenic peptide to the naive T-cell.
Dendritic cells acquired their name because they are covered with long membranous extension that resemble the dendrites of nerve cells. These extend and retract dynamically to increase the surface area to brows lymphocytes.
Ralph Steinman discovered the Dendritic cell (DC) in 1970 and awarding the Nobel Prize for this discovery in 2011.
LOCATION: Dendritic cells are bone marrow derived cells but they migrate to lymph node for activation. These are generally located on these parts of our body tissue which interact with the external environment like- skin, epithelial tissues. These are also present on the tissue of digestive tract and lung.
TYPES: There are different types of dendritic cells are present in our body. They are mainly differentiated as myeloid and lymphoid dendritic cells according to their origin. Langerhans cells are also one type of dendritic cell. All those types of are generated from haematopoietic stem cells (HSC) via different pathway.
FUNCTION OF DENDRITIC CELL: Dendritic cells are critical for the initiation of immune response. They perform distinct functions to induce immune response. It function is almost similar to the macrohage cell. They also play a vital role in antigen presentation via the expression of major histocompitibility complex (MHC).
They capture antigen in one location and present the antigen to another location. They recognize the extracellular foreign pathogenic antigen and become activated in outside of the lymph node. They engulf the pathogenic antigen by endocytosis. They processed the antigen and break it down into small peptides. Then they migrate to the lymph node, where they present the antigen to the naïve T-cell and initiate the adaptive immune response. They express high level of MHC-II molecule which paly the vital role in antigen presentation. These cell also posses class-I MHC molecule and they present the pathogenic antigen to both the T-helper cell and cytotoxic T-cell. The antigen-MHC-I complex present on the surface of the dendritic cell bind to the TCR (T-cell receptor) on the naïve cytotoxic T-cell and present the antigen to the naive T-helper cell via Ag-MHC-II complex. After this interaction the immature and naïve Cytotoxic and helper-T cell become mature and effective and induce the further immune response.
NOTABLE: The follicular dendritic cells do not arise in bone marrow and have completely different function from the other dendritic cells. They do not express MHC-II molecule so, cannot act in antigen presentation. They express membrane receptor for antibody (Ab) which allows binding of Ag-Ab complex or form immune complex.