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- Integrated immune response to non-self or altered-self elements (antigen(s)) is made up of a number of components. Some of these show unique specificity for the particular stimulating antigen(s) and comprise the specific or adaptive immune response, whilst others do not and comprise the nonspecific or innate immune response.
- The nonspecific response represents the first line response and can be considered cruder and more primitive. The cells and soluble mediators involved are primarily those associated with the processes of acute inflammation and endothelial cell activation.
- The specific response is more refined and usually invoked only in the face of either failure/continued stimulation of the nonspecific response. The cells responsible for the specific immune response are the lymphocytes; T, B and NK. The specificity they show for the inciting antigen is achieved via the use of specific antigen receptors, T cell and B cell receptors, expressed on cell surface.
- T cells recognize processed antigen via the TcR interacting with antigen presented by MHC-bearing
cells, leading to the secretion of additional cytokines and the generation of effector functions such as T cell help and T cell-mediated cytotoxicity brought about by the T-helper and T-cytotoxic subsets respectively. Historically, T cell responses have been termed the cellular immune response.
- B cells recognize native antigen and secrete soluble forms of the individual B cell antigen receptors which we recognize as antibodies. Historically, B cells and their antibody products have been termed the humoral immune response. Both T and B cells and their products are able to recruit and utilize components of the nonspecific response in a more effective and targeted manner, with the aim of eliminating or eradicating the antigen.
- In addition to demonstrating specificity, the specific immune response also demonstrates another critically important characteristic not seen with the nonspecific response - the memory for its encounter with all types of antigen. The benefit of this is that, on subsequent contact with the same antigen, the antigen can be eliminated more quickly and effectively, and with less tissue damage, than on the previous occasion.
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- Compare T and B lymphocytes.
- What are adhesion molecules and what is their role in the immune response?
- Can one distinguish T and B lymphocytes under a microscope?
- What is the role of the Fc fragment of an immunoglobulin?
- What is the role of the thymus in the immune response?
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| Roitt IM. Immunology, 5th edn. London: Mosby, 1998.
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| Janeway C, Traver P, Hunt S, Walport M. Immunobiology, 5th edn. London: Garland, 2002.
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| Chapel H, Heaney M, Misbah S, Snowden N. Essentials of Clinical Immunology, 4th edn. Oxford: Blackwell; 1999.
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Parkin J, Cohen B. An overview of the immune system. Lancet 2001;357:1777-1789.
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