cellular immune response.MOV

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. CD4 cells or helper T cells provide protection against different pathogens.

Please note that T cells cause death by apoptosis without using cytokines, therefore in cell mediated immunity cytokines are not always present.

Cellular immunity protects the body by: 1. 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;
2. activating macrophages and natural killer cells, enabling them to destroy intracellular pathogens; and
3. 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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• cellular
• immune
• response

[jawminsky]

This video is wrong or a million years old.

After phagocytosis of a viral particle, only dendritic cells can present viral antigen on MHC I via cross presentation. Furthermore, the dendritic cell doesn't need to be infected by the virus to present on MHC I and upon recognition, the T cell is activated to kill other infected cells, not the antigen presenting cell!