A primitive immune system
Article Abstract:
The immune system has been classified into two parts, the cellular and humoral systems. The cellular system includes the effector functions or actions of the cells of the immune system. The humoral system includes the action of the molecules, in particular antibody molecules that are secreted by the cells of the immune system in response to a specific antigen, a molecule that is recognized as foreign. Both the cellular and humoral systems contain complex receptors that can distinguish self from non-self and recognize specific foreign antigens. The question exists as to which, in evolution, developed first, the mechanisms that the cells use to carry out the immune functions, such as the killing of viral-infected cells, or the mechanisms that are needed to identify foreign substances. Cells must recognize molecules as foreign to activate additional cells of the immune system, and to make an effective immune response. It appears that a particular cell of the immune system, the natural killer (NK) cell, which does not contain receptors that are specific for particular antigens, may be a cell of the primitive immune system. NK cells can kill certain tumor cells and are involved in the early phases of the host defense against viral diseases. Other cells are involved in the later stages of immunity against viruses. It was not known how NK cells could recognize various foreign molecules without specific receptors. NK cells must have multispecific recognition mechanisms. Recently it was shown that NK contain the polypeptide zeta chain which is also found in other molecules of the immune system. It is thought to be involved in the transduction of a signal from the outside of the cell to the inside of the cell. The zeta chain may also be part of the primitive receptor of NK cells which allows the cell to recognize foreign molecules in general (not one specific molecule). NK cells may have evolved into T cells, another cell of the immune system which recognizes foreign molecules more specifically and is necessary for the development of an effective humoral response.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1989
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The class 1 MHC homologue of human cytomegalovirus inhibits attack by natural killer cells
Article Abstract:
The immune system seeks to control and eradicate virus infections by using class 1 major histocompatibility complex (MHC) restricted cytotoxic T lymphocytes (CTL). Many viruses have evolved strategies to escape detection and interference using a variety of mechanisms, which act to stop or reduce expression of MHC molecules on the cell's surface. Natural killer cells, however, attack cells without MHC molecules. A new viral strategy for evading immune surveillance by natural killer cells uses a MHC homologue.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 1997
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A purgative mastery
Article Abstract:
Research is presented describing the development of the human immune system and the way in which the thymus gland precariously balances the production and destruction of self-reactive cells.
Publication Name: Nature
Subject: Zoology and wildlife conservation
ISSN: 0028-0836
Year: 2001
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