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Cell-mediated immunity

 

 
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Cell-mediated immunity
 
 
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Cell-mediated immunity is an immune response that does not involve antibodies or complement
Complement system

The complement system is a biochemical cascade that helps clear pathogens from an organism. It is part of the larger immune system that is not adaptable and does not change over the course of an individual's lifetime; as such it belongs to the innate immunity....
 but rather involves the activation of macrophage
Macrophage

Macrophages are white blood cells within tissues, produced by the division of monocytes. Human macrophages are about 21 micrometres in diameter....
s, natural killer cell
Natural killer cell

Natural killer cells are a type of cytotoxic lymphocyte that constitute a major component of the innate immune system. NK cells play a major role in the rejection of tumors and cells infected by viruses....
s (NK), antigen
Antigen

An antigen is a substance that prompts the generation of antibodies and can cause an immune response. The word originated from the notion that they can stimulate antibody generation....
-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
Humoral immunity

The Humoral Immune Response is the aspect of immunity that is mediated by secreted antibodies produced in the cells of the B lymphocyte lineage ....
, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum
Blood plasma

Blood plasma is the liquid component of blood, in which the blood cells are suspended. It makes up about 55% of total blood volume. It is composed of mostly water , and contains dissolved proteins, glucose, clotting factors, mineral ions, Hormone and carbon dioxide ....
) and cellular immunity, for which the protective function of immunization was associated with cells.






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Cell-mediated immunity is an immune response that does not involve antibodies or complement
Complement system

The complement system is a biochemical cascade that helps clear pathogens from an organism. It is part of the larger immune system that is not adaptable and does not change over the course of an individual's lifetime; as such it belongs to the innate immunity....
 but rather involves the activation of macrophage
Macrophage

Macrophages are white blood cells within tissues, produced by the division of monocytes. Human macrophages are about 21 micrometres in diameter....
s, natural killer cell
Natural killer cell

Natural killer cells are a type of cytotoxic lymphocyte that constitute a major component of the innate immune system. NK cells play a major role in the rejection of tumors and cells infected by viruses....
s (NK), antigen
Antigen

An antigen is a substance that prompts the generation of antibodies and can cause an immune response. The word originated from the notion that they can stimulate antibody generation....
-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
Humoral immunity

The Humoral Immune Response is the aspect of immunity that is mediated by secreted antibodies produced in the cells of the B lymphocyte lineage ....
, for which the protective function of immunization could be found in the humor (cell-free bodily fluid or serum
Blood plasma

Blood plasma is the liquid component of blood, in which the blood cells are suspended. It makes up about 55% of total blood volume. It is composed of mostly water , and contains dissolved proteins, glucose, clotting factors, mineral ions, Hormone and carbon dioxide ....
) 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.

Cellular immunity protects the body by:

  1. activating antigen-specific cytotoxic T-lymphocytes that are able to induce apoptosis
    Apoptosis

    Apoptosis is the process of programmed cell death that may occur in multicellular organisms. Programmed Cell death involves a series of biochemical events leading to a characteristic cell Morphology and death, in more specific terms, a series of biochemical events that lead to a variety of morphological changes, including Bleb , changes...
     in body cells displaying epitopes of foreign antigen on their surface, such as virus
    Virus

    A virus is a Optical microscope#Limitations of light microscopes infectious agent that is unable to grow or reproduce outside a host cell . Viruses infect all cellular life....
    -infected cells, cells with intracellular bacteria, and cancer cells displaying tumor
    Tumor

    A tumor or tumour is the name for a swelling or lesion formed by an abnormal growth of cells . Tumor is not synonymous with cancer. A tumor can be Benign neoplasm, Carcinoma in situ or malignant, whereas cancer is by definition malignant....
     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, cancer
Cancer

Cancer is a class of diseases in which a group of cell display uncontrolled growth , invasion , and sometimes metastasis . These three malignant properties of cancers differentiate them from benign tumors, which are self-limited, do not invade or metastasize....
s, and intracellular bacteria. It also plays a major role in transplant rejection
Transplant rejection

Transplant rejection occurs when a Organ transplant organ or tissue is not accepted by the body of the transplant recipient. This is explained by the concept that the immune system of the recipient attacks the transplanted organ or tissue....
.