196:
456:
361:
314:, another component of the innate immune system, consists of three pathways that are activated in distinct ways. The classical pathway is triggered when IgG or IgM is bound to its target antigen on either the pathogen cell membrane or an antigen-bound antibody. The alternative pathway is activated by foreign surfaces such as viruses, fungi, bacteria, parasites, etc., and is capable of autoactivation due to “tickover” of C3. The
431:(IgD) antibodies specific to the particular B cell, must bind to the antigen which then results in internal processing so that it is presented on the MHC class II molecules of the B cell. Once this happens a T helper cell which is able to identify the antigen bound to the MHC interacts with its co-stimulatory molecule and activates the B cell. As a result, the B cell becomes a
419:. Several T cell subgroups can be activated by specific APCs, and each T cell is specially equipped to deal with each unique microbial pathogen. The type of T cell activated and the type of response generated depends, in part, on the context in which the APC first encountered the antigen. Once helper T cells are activated, they are able to activate naĂŻve B cells in the
394:. This is extremely important for B and T cell activation. B and T cells are extremely dangerous cells, and if they are able to attack without undergoing a rigorous process of activation, a faulty B or T cell can begin exterminating the host's own healthy cells. Activation of naĂŻve helper T cells occurs when
442:
Specificity in the adaptive branch is due to the fact that every B and T cell is different. Thus there is a diverse community of cells ready to recognize and attack a full range of invaders. The trade-off, however, is that the adaptive immune response is much slower than the body's innate response
214:
is an organism's first response to foreign invaders. This immune response is evolutionarily conserved across many different species, with all multi-cellular organisms having some sort of variation of an innate response. The innate immune system consists of physical barriers such as
414:
which are specially equipped not only with MHC class II but also with co-stimulatory ligands which are recognized by co-stimulatory receptors on helper T cells. Without the co-stimulatory molecules, the adaptive immune response would be inefficient and T cells would become
462:
Depending on exogenous demands, several types of immune response (IR) are distinguished. In this paradigm, immune system (both innate and adaptive) and non-immune system cellular and molecular components are organized to optimally respond to distinct exposome challenges.
159:
The first contact that an organism has with a particular antigen will result in the production of effector T and B cells which are activated cells that defend against the pathogen. The production of these effector cells as a result of the first-time exposure is called a
180:
introduce a weakened, killed, or fragmented microorganism in order to evoke a primary immune response. This is so that in the case that an exposure to the real pathogen occurs, the body can rely on the secondary immune response to quickly defend against it.
115:
The innate branch—the body's first reaction to an invader—is known to be a non-specific and quick response to any sort of pathogen . Components of the innate immune response include physical barriers like the skin and mucous membranes, immune cells such as
447:. After encountering an antigen, the immune system produces memory T and B cells which allow for a speedier, more robust immune response in the case that the organism ever encounters the same antigen again.
330:, bacteria, parasites, and viruses. Each of the three pathways ensures that complement will still be functional if one pathway ceases to work or a foreign invader is able to evade one of these pathways (
269:
When a foreign pathogen bypasses the physical barriers and enters an organism, the PRRs on macrophages will recognize and bind to specific PAMPs. This binding results in the activation of a
390:. The cells of the adaptive immune system are extremely specific because during early developmental stages the B and T cells develop antigen receptors that are specific to only certain
443:
because its cells are extremely specific and activation is required before it is able to actually act. In addition to specificity, the adaptive immune response is also known for
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739:
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586:
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immune response will kick in and the immune system will be able to respond in both a fast and strong manner because of the memory cells from the first exposure.
172:
are also produced in the case that the same pathogen enters the organism again. If the organism does happen to become re-exposed to the same pathogen, a
156:—also known as immunoglobulins—which directly interact with antigen and are a very important component for a strong response against an invader.
65:
In addition, there are other forms of immune response. For example, harmless exogenous factors (such as pollen and food components) can trigger
266:(LPS), both of which are essential components of bacteria and are therefore evolutionarily conserved across many different bacterial species.
255:
326:
aka specific pattern recognition receptors bind to pathogen-associated molecular patterns on the surface of invading microorganisms such as
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250:(PRR). These receptors are structures on the surface of macrophages which are capable of binding foreign invaders and thus initiating
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243:, the innate response is not specific to any one foreign invader and as a result, works quickly to rid the body of pathogens.
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247:
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IR targets extracellular bacteria and fungi by recruiting ILC3, Th17, neutrophils, opsonizing IgG isotypes.
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334:
principle). Though the pathways are activated differently, the overall role of the complement system is to
69:; latex and metals are also known allergens. A transplanted tissue (for example, blood) or organ can cause
1057:
471:
319:
203:
199:
107:
95:
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and thus, it takes longer to activate the components involved. The adaptive branch include cells such as
136:. On the other hand, the adaptive branch is the body's immune response which is catered against specific
339:
280:
to enter the nucleus of the macrophage and initiate the transcription and eventual secretion of various
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289:
274:
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which could cause serious problems to the health of the host organism if not cleared from the body.
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for the purpose of defending against exogenous factors. These include a wide variety of different
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423:. However, B cell activation is a two-step process. Firstly, B cell receptors, which are just
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to the infected tissue. Once neutrophils enter the tissue, like macrophages, they are able to
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can be observed in pregnant women. These special forms of immune response are classified as
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IR is elicited by viruses, intracellular bacteria, parasites. The actors here are group 1
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710:. Stranford, Sharon A.; Jones, Patricia P.; Owen, Judith A. (Eighth ed.). New York.
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which are integral structural components of pathogens. Examples of PAMPs include the
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493:, Th2 lymphocytes, eosinophils, basophils, mast cells, IgE are key players here.
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is a physiological reaction which occurs within an organism in the context of
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977:"Immune response patterns in non-communicable inflammatory skin diseases"
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236:
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100:, which work together to protect against pathogens. Both branches engage
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Additional types of IR can be observed in noninfectious pathologies.
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149:
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Reaction occurring within an organism as a defence against a pathogen
479:(ILC1), NK cells, Th1 cells, macrophages, opsonizing IgG isotypes.
486:
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359:
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43:
39:
754:"The Innate Immune System: Early Induced Innate Immunity: PAMPs"
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In general, there are two branches of the immune response, the
981:
Journal of the
European Academy of Dermatology and Venereology
844:
Bonilla FA, Oettgen HC (February 2010). "Adaptive immunity".
296:. Release of these cytokines is necessary for the entry of
906:
Annunziato F, Romagnani C, Romagnani S (December 2014).
254:
within the immune cell. Specifically, the PRRs identify
879:
Janeway CA, Travers P, Walport M, Shlomchik MJ (2001).
885:(5th ed.). New York and London: Garland Science.
678:"vaccine | Definition, Types, History, & Facts"
604:Clinical immunology : principles and practice
654:"Immune system – Evolution of the immune system"
466:Currently, several types of IR are classified.
954:(9th ed.). Garland Science. p. 451.
945:
943:
912:The Journal of Allergy and Clinical Immunology
846:The Journal of Allergy and Clinical Immunology
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837:
835:
256:pathogen-associated molecular patterns (PAMPs)
1028:Browse journals and books | ScienceDirect.com
81:. Another special form of immune response is
8:
606:. Rich, Robert R. (Fifth ed.). 2018.
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402:on their cell surface. These APCs include
246:Pathogens are recognized and detected via
1000:
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435:which secretes antibodies that act as an
1033:Experimental and Clinical Immunogenetics
782:Sarma, J. Vidya; Ward, Peter A. (2011).
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370:presentation along with co-stimulatory
73:. A type of immune reactivity known as
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975:Eyerich, K.; Eyerich, S. (May 2018).
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308:and kill any pathogens or microbes.
489:and multicellular parasites. ILC2,
239:and complement. In contrast to the
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338:pathogens and induce a series of
235:, and soluble factors including
128:, and soluble factors including
557:(Sixth ed.). Hoboken, NJ.
396:antigen-presenting cells (APCs)
1:
248:pattern recognition receptors
398:present foreign antigen via
950:Murphy K, Weaver C (2016).
555:How the immune system works
46:, intra- and extracellular
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925:10.1016/j.jaci.2014.11.001
858:10.1016/j.jaci.2009.09.017
553:Sompayrac, Lauren (2019).
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318:pathway is triggered when
223:, various cell types like
188:
800:10.1007/s00441-010-1034-0
71:graft-versus-host disease
788:Cell and Tissue Research
451:Types of immune response
384:adaptive immune response
356:Adaptive immune response
241:adaptive immune response
952:Janeway's Immunobiology
784:"The complement system"
682:Encyclopedia Britannica
658:Encyclopedia Britannica
260:peptidoglycan cell wall
852:(2 Suppl 2): S33–S40.
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400:MHC class II molecules
388:second line of defense
379:
340:inflammatory responses
320:mannose-binding lectin
212:innate immune response
207:
204:gram-negative bacteria
200:Innate immune response
638:) CS1 maint: others (
513:(T and B cells), and
505:All types of IR have
477:innate lymphoid cells
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354:Further information:
273:which allows for the
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189:Further information:
706:Punt, Jenni (2018).
445:immunological memory
342:that help to combat
275:transcription factor
191:Innate immune system
908:"Adaptive immunity"
264:lipopolysaccharides
18:Anamnestic response
758:faculty.ccbcmd.edu
509:(ILCs, NK cells),
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439:against invaders.
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83:antitumor immunity
993:10.1111/jdv.14673
271:signaling pathway
164:immune response.
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298:neutrophils
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1053:Immunology
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768:2020-03-08
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537:References
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