cellular immunity


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Related to cellular immunity: MHC, humoral immunity

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)

cellular immunity

cellular immunity

Etymology: L, cellula, little cell, immunis, exempt
the mechanism of acquired immunity characterized by the dominant role of T cell lymphocytes. Cellular immunity is involved in resistance to infectious diseases caused by viruses and some bacteria and in delayed hypersensitivity reactions, some aspects of resistance to cancer, certain autoimmune diseases, graft rejection, and certain allergies. It does not involve the production of humoral antibody but instead involves the activation of Mo and natural killer cells. Also called cell-mediated immunity. Compare humoral 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).
cell-mediated immunity
delayed hypersensitivity,
, cellular immunity (sel'mē'dē-āt-ĕd i-myū'ni-tē, sel'yū-lăr) Synonym(s): delayed hypersensitivity.

immunity

1. the condition of being immune; security against a particular disease; nonsusceptibility to the invasive or pathogenic effects of microorganisms or helminth parasites or to the toxic effect of antigenic substances. Called also functional or protective immunity.
2. responsiveness to antigen that leads to more rapid binding or elimination of antigen than in the nonimmune state; it includes both humoral and cell-mediated immunity (below).
3. the capacity to distinguish foreign material from self, and to neutralize, eliminate or metabolize that which is foreign (non-self) by the physiological mechanisms of the immune response.
The mechanisms of immunity are essentially concerned with the body's ability to recognize and dispose of substances which it interprets as foreign and sometimes harmful to its well-being. When such a substance enters the body, complex chemical and mechanical activities are set into motion to defend and protect the body's cells and tissues. The foreign substance, usually a protein, is called an antigen, that is, one which generates the production of an antagonist. The most readily recognized response to the antigen is the production of antibody. The antigen-antibody reaction is an essential component of the overall immune response. Of equal or greater importance to antibody, particularly for some antigens, is the development of so-called cell-mediated immune response, which involves clonal expansion of specifically reactive T lymphocytes including cytotoxic T lymphocytes (Tc lymphocytes) which play a major role in eliminating the foreign antigens that are cell associated.
Immunological responses in animals can be divided into two broad categories: humoral immunity, which refers to the production of antibody which becomes part of the body fluids (humors), especially serum, and cell-mediated or cellular immunity, which involves a variety of activities designed to destroy or at least contain cells that are recognized by the body as expressing foreign antigens on their cell surface, e.g. viral antigens. Both types of response are mediated by lymphocytes that originate in the bone marrow as stem cells and later are converted into mature cells having specific properties and functions.

acquired immunity
antigen specific immunity attributable to the production of antibody and of specific immune T lymphocytes (responsible for cell-mediated immunity), following exposure to an antigen, or passive transfer of antibody or immune lymphoid cells (adoptive immunity).
active immunity
that which follows exposure to an antigen; acquired immunity attributable to the presence of antibody or of immune lymphoid cells formed in response to antigenic stimulus. Called also adaptive immunity.
adoptive immunity
passive immunity of the cell-mediated type conferred by the administration of sensitized lymphocytes from an immune donor to a naive recipient.
artificial immunity
includes acquired (active) immunity produced by deliberate exposure to an antigen, such as a vaccine or the administration of antibody (passive).
cellular immunity
dependent upon T lymphocytes which are sensitized by first exposure to a specific antigen. Subsequent exposure stimulates the release of a group of substances known as lymphokines, such as interferon, and interleukins as well as direct killing by cytotoxic T lymphocytes.
functional immunity
see immunity (above).
humoral immunity
mediated by antibodies formed by antigen-specific B lymphocytes. Each B lymphocyte has monomeric IgM receptors which capture specific antigen, initiating production of the specific immunoglobulins. B lymphocytes activated by the presence of their specific antigen undergo transformation, lymphocyte blastogenesis, whereby they become metabolically active, divide, and some mature to plasma cells, which are major producers of antibodies. Some cells revert to small lymphocytes, 'memory' cells, and the expanded clone of these cells, on re-exposure to the antigen, undergo further lymphocyte blastogenesis, leading to further increased antibody production and numbers of memory cells.
There are two types of humoral immune response: primary and secondary. The primary response begins immediately after the inital contact with an antigen; the resulting antibody, predominantly IgM, appears 48 to 72 hours later. The secondary response occurs within 24 to 48 hours and produces large quantities of predominantly IgG. The secondary response persists much longer than the primary response and is the result of repeated contact with the antigens.
innate immunity, native immunity, natural immunity
natural immunity resulting from the genetic makeup of the host, before exposure to an antigen.
maternal immunity
that acquired by the neonate by transplacental transfer of immunoglobulins or from ingestion of colostrum or via the yolk sac in the case of birds. The placentation of all agricultural animals precludes trans-placental transfer of immunoglobulin. Passive transfer of maternal immunity is effected by the transfer of immunoglobulilns present in high concentration in the first milk, colostrum, through the intestine of the newborn. The success of this transfer is dependent upon the time after birth that colostrum is ingested (physiologically 24-36 hours, but effectively for adequate transfer, 8 hours after birth) and on the mass of immunoglobulin ingested which is determined by the concentration of immunoglobulin in colostrum and the amount of colostrum ingested.
Failure of passive transfer results in a significant increase in risk for neonatal disease. Neonates that fail to acquire serum concentrations of IgG1 greater than 10 mg/ml are at significantly higher risk of septicemic, enteric and respiratory disease. Failure of passive transfer occurs as a result of neonates sucking the dam or acquiring colostrum by artificial feeding too late in the absorptive process, or by receiving too little colostrum or receiving colostrum with low immunoglobulin concentration. See also passive immunity (below) and colostral immunoglobulin.
natural immunity
see innate immunity (above).
passive immunity
the transfer of antibodies from a donor in which they were produced to a recipient for temporary immunity. Can be in the form of serum or colostrum or yolk. Significant transplacental transfer of antibodies is found in primates, but does not occur in domestic animals. Passive immunity in domestic mammals comes via the colostrum, with its high concentration of antibodies, and the more than normally pervious epithelium of the neonate's intestinal epithelium. In birds maternal antibody is transferred to the yolk, from where the developing chick embryo absorbs it from about day 11 of incubation. See also passive immunization.
protective immunity
see immunity (above).
References in periodicals archive ?
Participant variables, including age, participation in other (or any) outdoor activities, and residential zip code, were assessed by logistic regression, and did not correlate with conversion of cellular immunity (data not shown).
It is thought that FIA stimulated humoral immunity reaction, while FCA helped both humoral and cellular immunity reaction.
It should be noted, however, that parameters of cellular immunity both in the group of healthy children from consanguineous marriage and in the group of children from the non consanguineous marriage are within the limits of the standard norms.
Suppressed cellular immunity in patients with nasopharyngeal carcinoma.
Cellular immunity to Propionebacterium acnes in normal population and patients with ache vulgaris.
Types of vaccines Type Examples Immunity due to: Live, attenuated Smallpox Antibodies Oral polio Heat killed: protein Polio Antibodies or subunit Hepatitis B Replication competent Yellow fever Antibodies Replication defective Adenovirus 5 Cellular immunity DNA Many in development Cellular immunity Prime/Boost Optimized strategy Both antibodies and for HIV cellular immunity Virus-like particles Many in development Both antibodies and (VLPs) cellular immunity Type Risks/Problems Live, attenuated Reversion to pathogenic Heat killed: protein Not very diverse, or subunit not as effective Replication competent Reversion Replication defective Pre-existing immunity DNA No antibodies Prime/Boost Complicated, expensive Virus-like particles Expensive to produce, (VLPs) unstable
They also did not find any correlation between virus-specific T-cell numbers and antibody titers, indicating that humoral and cellular immunity were regulated independently.
Recently, however, there has been renewed interest in antibodies -- partly because of growing knowledge about how to select the right antibodies, and also because cellular immunity alone may not prevent infection but only slow disease development.
lactis HN 019 has been an effective probiotic dietary supplement for enhancing some aspects of cellular immunity in the elderly.
Purification of the antigenic components of pigeon dropping extract, the responsible agent for cellular immunity in pigeon breeder's disease.
On activation of cellular immunity, the T-cell-derived cytokine interferon-[gamma] stimulates the enzyme indoleamine-(2,3)-dioxygenase (IDO) in various cells (3, 4).

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