Cell-mediated immunity


Cell-mediated immunity

Cell-mediated immunity is an immune response that does not involve antibodies or complement but rather involves the activation of macrophages, natural killer cells (NK), antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. Historically, the immune system was separated into two branches: humoral immunity, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum) and cellular immunity, for which the protective function of immunization was associated with cells.

Cellular immunity protects the body by:

# activating antigen-specific cytotoxic T-lymphocytes that are able to induce apoptosis in body cells displaying epitopes of foreign antigen on their surface, such as virus-infected cells, cells with intracellular bacteria, and cancer cells displaying tumor antigens;
# activating macrophages and natural killer cells, enabling them to destroy intracellular pathogens; and
# stimulating cells to secrete a variety of cytokines that influence the function of other cells involved in adaptive immune responses and innate immune responses.

Cell-mediated immunity is directed primarily at microbes that survive in phagocytes and microbes that infect non-phagocytic cells. It is most effective in removing virus-infected cells, but also participates in defending against fungi, protozoans, cancers, and intracellular bacteria. It also plays a major role in transplant rejection.


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Look at other dictionaries:

  • cell-mediated immunity — /sel mee dee ay tid/, Immunol. immunity independent of antibody but dependent on the recognition of antigen by T cells and their subsequent destruction of cells bearing the antigen or on the secretion by T cells of lymphokines that enhance the… …   Useful english dictionary

  • cell-mediated immunity — cell′ me diated immu′nity n. imu immunity conferred to an individual through the activity of T cells, involving the direct destruction of viruses, foreign particles, etc Compare antibody mediated immunity • Etymology: 1970–75 …   From formal English to slang

  • cell-mediated immunity — /sel mee dee ay tid/, Immunol. immunity independent of antibody but dependent on the recognition of antigen by T cells and their subsequent destruction of cells bearing the antigen or on the secretion by T cells of lymphokines that enhance the… …   Universalium

  • cell-mediated immunity — noun Immunity as a result of a cell mediated immune response …   Wiktionary

  • cell-mediated immunity — (CMI), cellular immunity immunity mediated by T lymphocytes either through release of lymphokines or through exertion of direct cytotoxicity, transmissible by transfer of lymphocytes but not serum; it includes type IV hypersensitivity reactions,… …   Medical dictionary

  • cell-mediated immunity — The type of immunity that results from T cells coming into close contact with foreign cells or infected cells to destroy them; it can be transferred to a nonimmune individual by the transfer of cells …   Dictionary of microbiology

  • cell-mediated immunity — (Medicine) cellular immunity activated by T lymphocytes (rather than antibodies), CMI …   English contemporary dictionary

  • cell mediated immunity — Immune response that involves effector T lymphocytes and not the production of humoral antibody. Responsible for allograft rejection, delayed hypersensitivity and in defence against viral infection and intracellular protozoan parasites …   Dictionary of molecular biology

  • cell-mediated — cell me·di·at·ed sel .mēd ē .āt əd adj relating to or being the part of immunity or the immune response that is mediated primarily by T cells and esp. cytotoxic T cells rather than by antibodies secreted by B cells <cell mediated immunity>… …   Medical dictionary

  • cell-mediated — adjective : relating to or being the part of immunity or the immune response that is mediated primarily by T cells and especially cytotoxic T cells rather than by antibodies secreted by B cells cell mediated immunity cell mediated reactions… …   Useful english dictionary


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