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Antigen presentation stimulates T cells to become either "cytotoxic" CD8+ cells or "helper" CD4+ cells.. A cytotoxic T cell (also known as T C, cytotoxic T lymphocyte, CTL, T-killer cell, cytolytic T cell, CD8 + T-cell or killer T cell) is a T lymphocyte (a type of white blood cell) that kills cancer cells, cells that are infected by intracellular pathogens such as viruses or bacteria, or ...
These cells are defined by the expression of the CD8 protein on their cell surface. Cytotoxic T cells recognize their targets by binding to short peptides (8-11 amino acids in length) associated with MHC class I molecules, present on the surface of all nucleated cells. Cytotoxic T cells also produce the key cytokines IL-2 and IFNγ.
CTLs are able to eliminate most cells in the body since most nucleated cells express class I MHC molecules. The CTL-mediated immune system can be divided into two phases. In the first phase, functional effector CTLs are generated from naive T c cells through activation and differentiation. In the second phase, affector CTLs destroy target cells ...
An immune checkpoint regulator is a modulator of the immune system, that allows initiation of a productive immune response and prevents the onset of autoimmunity. Examples of such a molecule are cytotoxic T-lymphocyte antigen 4 (CTLA-4 or CD152), which is an inhibitory receptor found on immune cells and programmed cell death 1 (CD279), which has an important role in down-regulating the immune ...
In the late 19th century Hippocratic tradition medicine system, the immune system was imagined 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.
Antigen presentation is a vital immune process that is essential for T cell immune response triggering. Because T cells recognize only fragmented antigens displayed on cell surfaces, antigen processing must occur before the antigen fragment can be recognized by a T-cell receptor.
Once mature, T cells emigrate from the thymus to provide vital functions in the immune system. [11] [12] Each T cell has a distinct T cell receptor, suited to a specific substance, called an antigen. [12] Most T cell receptors bind to the major histocompatibility complex on cells of the body.
They are protein mediators typically produced by T cells to direct the immune system response by signaling between its cells. Lymphokines have many roles, including the attraction of other immune cells, including macrophages and other lymphocytes, to an infected site and their subsequent activation to prepare them to mount an immune response.