Cell-mediated immunity is an immune response that does not involve antibodies but rather involves the activation of macrophages and natural killer cells, the production of antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. These mechanisms are described below.
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.
Natural Killer Cells
|These destroy intracellular pathogens.|
|T-Lymphocytes||Activation of antigen-specific cytotoxic T-lymphocytes allows them to lyse body cells, displaying epitopes of foreign antigens on their surface. This is particularly useful for virus-infected cells, cells with intracellular bacteria and cancer cells with tumor antigens.|
|Cytokines||Stimulating cells to secrete a variety of cytokines allows them to influence the function of other cells involved in adaptive and innate immune responses.|