Immunology
Immunologyis the study of theimmune system.The immune system is the parts of the body which work againstinfectionandparasitismby other living things. Immunology deals with the working of the immune system in health and diseases, and with malfunctions of the immune system.
An immune system is present in all plants and animals. We know this because biologists have found genes coding fortoll-like receptorsin many differentmetazoans.[1]These toll-like receptors can recognisebacteriaas 'foreign', and are the starting-point for immune reactions. The type ofimmunitywhich is triggered by the toll-like receptors is calledinnate immunity.This is because it is entirelyinheritedin ourgenome,and is fully working as soon as ourtissuesandorgansare properly developed.
Vertebrates,and only vertebrates,have a second type of immunity. This is calledadaptive immunity,because it 'remembers' previous infections. Then, if the same infection occurs again, the reaction is much stronger and faster. This immunological memory "confers a tremendous survival advantage" and with it vertebrates "can survive over a long lifetime in a pathogen-filled environment".[1]
Types of immunity in vertebrates
[change|change source]Innate immune response
[change|change source]Theinnate immune systemis usually means all of thecellsand systems that does not have to be exposed to a particularpathogenbefore they can work.
Innate immunity starts with theskin,which is an excellent barrier toinfection.
Adaptive immune response
[change|change source]Theadaptive immune systemincludes cells and systems that do require previous exposure to a pathogen. It explains the unique ability of the mammalian immune system to remember previous infections and mount a rapid and robust reaction to secondary infections. Thisimmunological memoryis due to the biology ofT-cellsandB-cells.
Other aspects of immunity
[change|change source]Vaccinesboost the acquired immune system by offering weak forms of infection that the body can fight off. The system remembers how to do it again when a stronger infection happens. If the vaccine works, the body can then fight off a serious infection.
The distribution of vaccines and other immune system affectingcurescan be considered another level of acquired immune system, one governed by access tovaccinationandmedicinein general. The intersection of this with the spread ofdisease(as studied inepidemiology) is part of the field ofpublic health.
Errors and weaknesses
[change|change source]Errors of the immune system may cause damage. Inautoimmune diseases,the body attacks parts of itself because the system mistakes some parts of the body as 'foreign'. Some kinds ofarthritisare caused this way.
Sometimes serious pathogens slip in because their surface is disguised as something the host cell walls can accept. That is how viruses work. Once inside a cell, their genetic material controls the cell. Infections likeHIVget in this way, and then attack cells which are the basis of the immune system. Artificial means are often used to restore immune system function in an HIV-challenged body, and prevent the onset ofAIDS.This is one of the most complex issues in immunology as it involves every level of that system. This research during the 1980s and 1990s radically changed the view of the human immune system and its functions and integration in thehuman body.
History of immunology
[change|change source]Immunology is a science that examines the structure and function of the immune system. It originates frommedicineand early studies on the causes of immunity to disease. The earliest known mention of immunity was during theplague of Athensin 430 BC.Thucydides(460–395 BC) noted that people who had recovered from a previous bout of some diseases could nurse the sick without contracting the illness a second time.[2]
In the 18th century,Pierre-Louis Moreau de Maupertuismade experiments with scorpion venom and observed that certain dogs and mice were immune to this venom.[3]This and other observations of acquired immunity led toLouis Pasteur(1822–1895) developingvaccinationand thegerm theory of disease.[4]Pasteur's theory was in direct opposition to contemporary theories of disease, such as themiasma theory.It was not until the proofsRobert Koch(1843–1910) published in 1891 (for which he was awarded aNobel Prizein 1905) thatmicroorganismswere confirmed as the cause ofinfectious disease.[5]Viruses were confirmed as human pathogens in 1901, when theyellow fevervirus was discovered byWalter Reed(1851–1902).[6]
Immunology made a great advance towards the end of the 19th century, through rapid developments, in the study ofhumoral immunity[7]and cellular immunity.[8]Particularly important was the work ofPaul Ehrlich(1854–1915), who proposed theside-chain theoryto explain the specificity of the antigen-antibody reaction. The Nobel Prize for 1908 was jointly awarded to Ehrlich and the founder of cellular immunology,Ilya Mechnikov(1845–1916).[9]
The simplest form of immunity is theDNA restrictionsystem inbacteriathat preventsinfectionbybacteriophages.
References
[change|change source]
- ↑1.01.1Janeway, Charles A. 2001. Evolution of the imune system: past, present and future. In Janeway C.A; Travers P; Walport M. & Shlomchik M. 2011.Immunobiology: the immune system in health and disease.5th ed, Garland, New York. 597–611ISBN0-8153-3642-X
- ↑Retief FP, Cilliers L (1998). "The epidemic of Athens, 430–426 BC".South African Medical Journal.88(1): 50–53.PMID9539938.
- ↑Ostoya P (1954)."Maupertuis et la biologie".Revue d'histoire des sciences et de leurs applications.7(1): 60–78.doi:10.3406/rhs.1954.3379.
- ↑Plotkin SA (2005)."Vaccines: past, present and future".Nature Medicine.11(4 Suppl): S5–11.doi:10.1038/nm1209.PMC7095920.PMID15812490.
- ↑The Nobel Prize in Physiology or Medicine 1905,Nobelprize.org, accessed 8 January 2007
- ↑Major Walter Reed, U.S. Army,Walter Reed Army Medical Center, accessed 8 January 2007.
- ↑In humoral immunity, antibodies are secreted into bodily fluids such as blood andlymph.
- ↑Mechnikov, Ilya; translated by F.G. Binnie (1905).Immunity in infective diseases(full text version: Google Books).Cambridge University Press.ISBN0548-64719-4.
- ↑ The Nobel Prize in Physiology or Medicine 1908Nobelprize.org, accessed 8 January 2007