Cell-mediated immunity

Cell-mediated immunity is a type of immune response that involves the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen. This immune response is primarily regulated by T cells, and it is critical for the elimination of pathogens that survive within cells, including viruses and bacteria, as well as for fighting fungal infections, cancer cells, and foreign tissues (in transplant rejection).

Overview

Cell-mediated immunity is an immune response that does not involve antibodies. Instead, this response relies on the activation of phagocytes, antigen-specific cytotoxic T-lymphocytes, and the release of various cytokines in response to an antigen.

Role of T cells

T cells play a crucial role in cell-mediated immunity. They are a type of white blood cell that circulate around our bodies, scanning for cellular abnormalities and infections. The T cell is essential for triggering the appropriate immune response.

Cytotoxic T cells

Cytotoxic T cells (also known as CD8+ T cells) are a type of T cell that kill cancer cells, cells that are infected (particularly with viruses), or cells that are damaged in other ways.

Helper T cells

Helper T cells (Th cells) assist other white blood cells in immunologic processes, including maturation of B cells into plasma cells and memory B cells, and activation of cytotoxic T cells and macrophages. These cells are also known as CD4+ T cells.

Immune response

In cell-mediated immunity, the cells of the immune system work together to recognize and destroy the cells that have been infected by a pathogen or transformed by cancer. The process begins when a macrophage ingests a pathogen and presents fragments of the pathogen on its surface. These fragments are recognized by T cells, which then initiate a series of responses to eliminate the pathogen.

See also

• Humoral immunity
• Innate immune system
• Adaptive immune system
• Immunology

References

• 
  Killer T cells surround a cancer cell