免疫学特异性免疫与免疫细胞英文.ppt

Two major T cell subsets Delayed hypersensitivity T cells and regulatory T cells Delayed hypersensitivity T cells (Td) are a subpopulation of TH cells They secrete a variety of cytokines and set up inflammatory response Regulatory T cells control the intensity of immune response They produce cytokines that turn down the immune response Three types of regulatory T cells exist Natural TReg cells: present in host before exposure to pathogen T regulatory 1 (TR1) cells: secrete cytokine IL10 T helper 3 (TH3) cells: secrete transforming growth factor B Natural killer (NK) cells A type of lymphocytes produced in bone marrow Present in blood, bone marrow and spleen Less frequent in lymph nodes and thymus Clearly different from T and B cells Useful in defence against viral infections Also have a role in protection against spreading of tumours (cancer) Important cytokines Monocytes and Macrophages Monocytes and macrophages originate from granulocyte monocyte progenitor cells in the bone marrow Some of the mature monocytes enter blood circulation Others enter tissues such as lymph nodes, spleen, liver and lung to develop as macrophages Both have enzymes in the cytoplasm and antigens on the surface Also, they have MHC molecules Macrophages are key cells for antigen processing and presentation – antigen presenting cells (APC) Dendritic cells Have long membrane extensions Resemble nerve cells Important in antigen processing and presentation (APC) Classified based on location Langerhans cells: found in the epidermis and mucous membranes Interstitial dendritic cells: found in most organs, e.g. heart, lungs, liver and kidney Interdigitating dendritic cells: found in T cell areas of secondary lymphoid tissue and the thymus Circulating dendritic cells: found in the blood and lymph (also known as veiled cells) Movement of dendritic cells from epidermis to lymph node Antigen processing TH cell activation Antibody production Cell-mediated immune response Antigen processing Activation