An antigen presenting cell like dendritic cell is a part of adaptive immune system. When it encounters a harmful foreign antigen, it engulfs it via phagocytosis. The phagocytic vesicle fuses with the intracellular lysosome and here the antigen is broken into smaller fragments. With the help of MHC complex, these fragments are presented on the surface of dendritic cell hence it becomes an antigen presenting cell. This cell is then recognized by other cells of immune system like lymphocytes and destroyed.
Dendritic cells are present in skin and lining of lungs, nose, stomach, intestines. In skin they are called as Langerhans cells. Macrophages are another type of antigen presenting cells.
