Cell-mediated immunity 569705 220280608 2008-06-19T02:43:56Z JForget 1064243 Reverted edits by [[Special:Contributions/124.254.82.109|124.254.82.109]] ([[User talk:124.254.82.109|talk]]) to last version by 170.223.207.25 '''Cell-mediated immunity''' is an [[immune response]] that does not involve [[antibodies]] or [[complement system|complement]] but rather involves the activation of [[macrophage]]s, [[natural killer cell]]s (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 [[blood plasma|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 [[bacterium|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]], [[protozoan]]s, [[cancer]]s, and intracellular bacteria. It also plays a major role in [[transplant rejection]]. {{Blood}} {{Immune_system}} [[Category:Immune system]] {{immunology-stub}} [[ar:مناعة خلوية]] [[es:Inmunidad celular]] [[id:Kekebalan selular]] [[it:Immunità cellulare]] [[pl:Odpowiedź odpornościowa komórkowa]] [[pt:Imunidade mediada por célula]] [[sv:Cell-medierad immunitet]]