Antigen-Presenting Cells
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Introduction
Following phagocytosis, neutrophils and macrophages exocytose digested bacterial fragments. Dendritic cells take up these bits, digest them into peptides, and express them on MHC Class II molecules.
Dendritic cells then migrate to peripheral lymph nodes, where they present antigen to CD4+ cells. Interaction with MHC class II with T Cell receptors induces CD4+ activation.
Macrophages can also antigen presenting cells, but they remain on site and present antigen to memory T cells in the area.
As only one in 105 lymphocytes recognizes a particular antigen, a large number of B or T cells must contact with either antigen or an antigen-presenting cell in order for a specific immune response to be generated.
Dendritic cells are important antigen-presenting cells located throughout the body.
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