cell-mediated immunity

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cell-·me·di·at·ed im·mu·ni·ty (CMI),

, cellular immunity
Immune responses mediated by activated, antigen-specific T lymphocytes. These T cells may function as effector cells or may orchestrate propagation of the inflammatory response and cellular recruitment through their secretion of cytokines and chemokines.
Synonym(s): delayed hypersensitivity (1)

cell-mediated immunity

Immunity resulting from a cell-mediated immune response. Also called cellular immunity.

cell-mediated immunity

cell-me·di·at·ed im·mu·ni·ty

, cellular immunity (CMI) (sel'mē'dē-āt-ĕd i-myū'ni-tē, sel'yū-lăr)
Immune responses that are initiated by T lymphocytes and mediated by T lymphocytes, macrophages, or both (e.g., graft rejection, delayed-type hypersensitivity).
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cell-mediated immunity

Abbreviation: CMI.
The regulatory and cytotoxic activities of T cells during the specific immune response. This process requires about 36 hr to reach its full effect. Synonym: T-cell–mediated immunity See: illustration; humoral immunity

Unlike B cells, T cells cannot recognize foreign antigens on their own. Foreign antigens are recognized by antigen-presenting cells (APCs) such as macrophages, which engulf them and display part of the antigens on the APC's surface next to a histocompatibility or “self-” antigen (macrophage processing). The presence of these two markers, plus the cytokine interleukin-1 (IL-1) secreted by the APCs activates CD4 helper T cells (TH cells), which regulate the activities of other cells involved in the immune response.

CMI includes direct lysis of target cells by cytotoxic T cells, creation of memory cells that trigger a rapid response when a foreign antigen is encountered for the second time, and delayed hypersensitivity to tissue and organ transplants. T cells also stimulate the activity of macrophages, B cells, and natural killer cells. These functions are controlled largely by the secretion of lymphokines such as the interleukins, interferons, and colony-stimulating factors. Lymphokines facilitate communication and proliferation of the cells in the immune system.

See also: immunity

cell-mediated immunity

Action by the immune system involving T cells (T LYMPHOCYTES) and concerned with protection against viruses, fungi, TUBERCULOSIS and cancers and rejection of foreign grafted material. Cell-mediated immunity is not primarily effected by ANTIBODIES.


effected by cellular rather than chemical elements.

cell-mediated hypersensitivity
see delayed hypersensitivity.
cell-mediated immunity
see cellular immunity.
cell-mediated lympholysis assay
a test of cell-mediated immunity in which activated cytoxic T lymphocytes cause lysis of 51Cr-labeled target cells.
References in periodicals archive ?
We approached this problem with the understanding that impaired cell-mediated immunity can result from the inhibition in antigen presentation to CD[8.
An evolving model of pregnancy-associated immune changes suggests that the hormonal environment of pregnancy contributes to local suppression of cell-mediated immunity at the maternal-fetal interface while mediating a systemic change toward Th2 dominance.
A major effect has been suppression of cell-mediated immunity (CMI), most notably an impairment of delayed-type hypersensitivity, which has been a consistent observation at low-dose levels in different species (Pier et al.
They include local ischemia secondary to vasoconstriction, chemical irritation from adulterants put in "cut" cocaine, and infection secondary to trauma, decreased humoral and cell-mediated immunity, and impaired mucociliary transport:
Investigators suspect that rhIL-12 enhances cell-mediated immunity by inducing interferon-[gamma] production and by augmenting natural killer cell cytotoxicity and cytotoxic T-cell proliferation and function.
The etiologic factors that cause sinonasal polyposis are still unclear, but there is evidence that cell-mediated immunity might play a role in its pathogenesis.
Some researchers worry that exaggerated cell-mediated immunity could develop into autoimmune disease, in which the immune system attacks the body's own tissues.
IL-12 is the primary cytokine that can influence the development of cell-mediated immunity.
A vaccine approach based on cell-mediated immunity that avoids some of these drawbacks is discussed here.
It is not known whether they retain cell-mediated immunity from their initial immunizations or whether they remain unprotected.
DEPs may also suppress cell-mediated immunity by inhibiting ANJ secretion of IL-12, a key cytokine for the initiation of T helper type 1 cell development in Listeria infection.
Such benefits include inhibition of tumors, extension of functional life, reduced body weight, improved cell-mediated immunity, and increased antioxidant defenses.

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