Preferred Label : Dendritic Cell Pathway;
NCIt related terms : Dendritic cells in regulating TH1 and TH2 Development;
Alternative definition : BIOCARTA: While T cells and B cells carry out the actions of antigen-specific immune
responses, antigen-presenting cells called dendritic cells are required for this to
happen. The name of dendritic cells is based on their shape, with activated dendritic
cells displaying long processes on their surface. When immature dendritic cells found
throughout the body internalize and present antigen, they express markers that stimulate
the activation of lymphocytes, and migrate to lymphocyte rich tissues like the spleen
and lymph nodes to initiate immune responses. In addition to stimulating responses
against antigens, dendritic cells also produce tolerance to self antigens. Dendritic
cells can be derived from either myeloid or lymphoid lineages. Monocyte (myeloid)
derived lineages (pDC1) stimulate Th1 cell differentiation while plasmacytoid (lymphoid)
dendritic cells (pDC2) induce Th2 cell differentiation. Factors that stimulate the
maturation of monocytes derived dendritic cells include GM-CSF, and IL-4. IL-3 stimulates
the differentiation of pDC2 cells into DC2 cells. A variety of factors are involved
in antigen-recognition and processing by immature dendritic cells and in the maturation
of these cells. The transition to mature dendritic cells down-regulates the factors
involved in antigen internalization, and increases the expression of MHC, costimulatory
molecules involved in lymphocyte activation, adhesion molecules, and specific cytokines
and chemokines. Toll-like receptors on the surface of immature dendritic cells recognize
microbial components to induce dendritic cell maturation. In addition to stimulating
B cell responses, dendritic cells are potent activators of T cells. IL-12 secretion
by dendritic cells stimulates T cell responses, particularly differentiation of Th1
cells that produce interferon-gamma and other pro-inflammatory cytokines. While IL-4
generally stimulates Th2 differentiation, the stimulation of Th2 cell formation by
DC2 cells does not appear to involve IL-4. The stimulation of Th1 and Th2 cell formation
by dendritic cells appears to be balanced by counter-regulation of each pathway by
the other. Interferon-gamma produced by Th1 cells blocks the further stimulation of
Th1 differentiation by DC1 cells. The IL-4 produced by Th2 cells kills dendritic cell
precursors that contribute to Th2 cell creation. Direct interactions between T cells
and dendritic cells are enhanced through the expression of adhesion molecules and
costimulatory receptors CD80 and CD86 expressed by mature dendritic cells activate
T cells in concert with the recognition of antigen/MHC by the T cell receptor. The
central role of dendritic cells as modulators of immune responses makes them an important
focus of studies about autoimmune disease, transplant rejection, allergies, responses
to infections, and other alterations of the immune response. (This definition may
be outdated - see the DesignNote.);
NCIt note : The BIOCARTA Definition (ALT_DEFINITION) for this pathway concept was provided by
BioCarta. This property was not created by, nor is it maintained by the NCI Thesaurus
staff. Additionally, BioCarta is no longer updating its pathway data; thus, the BIOCARTA
Definition might be outdated or inaccurate. Please see the Terms and Conditions for
Use at http://www.biocarta.com/.;
Biocarta ID : h_dcPathway;
Origin ID : C39048;
UMLS CUI : C1511763;
Semantic type(s)
- has_gene_product_element
- pathway_has_gene_element
