The Difference between Innate and Adaptive Immune Response - Coursework Example

Student’s Name: Institution of Learning: Instructor’s Name: Course Name: The Diffеrеnсе Bеtwееn Innate and Аdарtivе Immune Rеsроnsе The immune system is made up of defence mechanisms employed by the body against pathogens and toxins. Primarily, the immune system is composed of individual cells spread all over the body which work collaboratively to provide a clear defence function for the body. According to Porth the main role of the immune system is to protect the body against infection by recognizing and responding to antigens (Porth 321). Accordingly, the immune system provides defence through two main mechanisms. These include the innate or no-responsive immune response system that protects the body from all harmful substances or invaders; and the adaptive or specific immune response system that provides specific defence against specific antigens. This essay discusses the two immune response mechanisms that is innate and adaptive, to explain the differences between them. Definition of Terms Innate Immune Responses: Ygberg and Nilsson define innate immune responses as those components of the immune system that control and trigger immediate defence mechanisms, and which do not depend on previous exposure to a particular pathogen to elicit a response (Ygberg and Nilsson 121). The innate immune system is made up of cells and proteins that are continually present and prepared to activate and fight antigens or microbes at the infection sites. Consequently, the innate immune response system has three main functions: host protection in the initial infection stages through nonspecific recognition of a pathogen using conserved biological patterns (Ygberg and Nilsson 121); recruitment of the adaptive immune reaction; and definition of the nature of adaptive response required (Goldstein 242). As such, the core components of this immune system are phagocytic leukocytes, physical epithelial barriers, dendritic cells, natural killer (NK) cells, and circulating plasma proteins. Adaptive Immune Responses: According to Ygberg and Nilsson, adaptive or acquired immune response denotes those immune responses that are specific to particular antigens or pathogens (Ygberg and Nilsson 122). The adaptive immune response is recruited into action, to eliminate pathogens that evade or overcome innate immune defence mechanisms. This is accomplished through the action of two main responses including the humoral immunity facilitated by antibodies generated by the B cells and cell mediated immunity, facilitated by the T Cells (Porth 321). Further, components of this immune system are usually silent; though, when activated, these elements “adapt” to the existence of pathogens by triggering, proliferating, and generating potent mechanisms for counteracting or eradicating the pathogens. As such, this system provides a more efficient defence against a specific pathogen or antigen, but it requires more time to coordinate and develop a response. The hallmark feature of adaptive immune responses is the specific identification of pathogen that results into the creation of pathogen specific long-term memory (Rock, Lai and Kono). Differences between Innate and Adaptive Immune Response Systems Even though the innate and adaptive immune response systems function together to defend the body against infections, they exhibit differences in a number of levels such as the cell property, receptor property, pathogen recognition, action time and evolution (Twycross 11). At the cellular level, the adaptive immune response system is structured around three main classes of cells that are T cells, B cells and antigen-presenting cells (APCs); whereas the innate immune response system consists of numerous cell classes including dendritic cells (DC s), the natural killer (NK) cells, and phagocytic cells such as macrophages, neutrophils and eosinophils (Minnicozzi, Sawyer and Fenton 106). Additionally, these classes of cells are further segmented into different categories, including immature, semi mature or mature DC and naive or helper T cell. The second difference between the two immune response systems is observed at the receptor level. Characteristically, the multiple cells types within the innate immune response system generate germline-encoded pattern recognition receptors that recognize or identify danger-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs) (Minnicozzi, Sawyer and Fenton 106). In other words, the structure of innate immune system receptors is defined by the cell genome and has an invariant, genetically-determined specificity. Moreover, receptors within this system do not require gene segment rearrangement, and on a population level, this results in a non-clonal distribution of receptors on the system cells, implying that all identical cell types possess receptors with similar specificities (Kumar, Kawai and Akira). On the other hand, cells within the adaptive immune response system have somatically produced variable-region receptors like the BCR and TCR (B and T cell receptors) with variable specificities. These are generated by a multidimensional process of rearranging the gene segment within the cell. Further, receptors within the adaptive immune response system cells are distributed clonally, whereby there are subpopulations of a particular cell type (clones) which collectively have receptors with matching specificities, but that commonly, identical cell types possess receptors with distinct specificities (Twycross 12). Another difference between the innate and adaptive immune response system is exhibited in the nature of pathogen recognition. In the adaptive immune response system, the variable-region receptors react to the characteristics of pathogen structure: whereby, BCRs expressly recognise the peptide sequences on pathogens, including elements of bacterial cell membranes; and TCRs recognise peptide sequences manifesting as portions of the MHC- peptide complex (Takeuchi and Akira 75). Such receptors are carefully chosen for or in the course of the organism’s lifetime through the processes of clonal expansion and anergy or deletion. These receptors are also under adaptive pressure, rather than evolutionary. On the contrary, receptors in the innate immune response recognise a genetically-defined pattern of ligands under evolutionary pressure. In other words, the recognition of pathogens in this system, depends on the conserved genetic patterns (PAMPS) exposed or expressed by the pathogens. Accordingly, one main group of receptors in the innate immune response is the pattern recognition receptor (PRR), which distinguishes the evolutionary conserved PAMPs (Kirkman, Libbey and Wilcox 455). PRRs include receptors such as toll-like receptors, RIG-like receptors and NOD-like receptors (Ygberg and Nilsson 121). Further, PRRs are unable to distinguish a specific characteristic of a specific pathogen as compared to the variable-region receptors; instead, they are able to recognise conjoint features or produces of a whole class of pathogens. Consequently, innate immune response receptors are designated as non-specific while adaptive immune response receptors are labelled as specific. Another difference is observed at the response and action time level whereby the innate immune response system responds by producing cytokines (in the macrophages) and chemokines that meditate both inflammatory and lymphocyte response. The action time of the innate response system relies on immediate and maximal effector activation, to destroy the pathogen and is approximately zero to twelve hours after infection (Porth 322). In contrast, the adaptive or acquired immune response system employs the adaptation of variable-region receptors to match pathogens that are rapider in their evolution. This is accomplished through cell selection processes such as deletion and anergy and clonal expansion, which may take several days due to the delayed effector activation (Mantovani, Cassatella and Constantini). Another difference between these systems is also observed in that the innate immune response system cells lack an immunological memory of pathogens encountered and will react with the same potency upon recurrent exposure to the same pathogen. Conversely, the adaptive or acquired immune response system develops an immunological memory of specific pathogens encountered and is able to initiate a strong response when the pathogen is detected. This memory may be both passive or short term and active long -term memory (Rock, Lai and Kono). Lastly, evolution is present in the innate immune responses of both invertebrates and vertebrates whereas, in adaptive immune responses, evolution occurs only in vertebrates. Conclusion In summation, the immune system comprises of mechanisms that detect and eliminate pathogens, or antigens that may cause damage or infection to the host. This is accomplished through the collective action of two distinctive immune response subsystems: the innate and adaptive or acquired immune systems. These immune response subsystems have distinct structural and functional characteristics at the cell, receptor, recognition, response, action time and evolutionary levels. Primarily, each subsystem is comprised of different cell classes, which function differently and generate varied repertoires of receptors. These cells recognise their environment using receptors and create molecules like chemokines or cytokines which attach to pathogen cell receptors to control and limit their behaviour. Moreover, adaptive or acquired immune response variable-region receptors are carefully chosen in the course of the host’s lifetime while the features of innate immune response pattern recognition receptors (PRRs) are static and genetically defined. Lastly, whereas these cells are all created from similar progenitor cells, they mature along separate differentiation pathways in reaction to the varied signals they obtain using their receptors. Works Cited Goldstein, Daniel R. . "Role of Aging on Innate Responses to Viral Infections." J Gerontol A Biol Sci Med Sci. 67A(3) (2012): 242–246. Kirkman, Nikki J. , et al. "Innate but not adaptive immune responses contribute to behavioral seizures following viral infection." Epilepsia, 51(3) (2010): 454–464. Kumar, Himanshu, Taro Kawai and Shizuo Akira. "Pathogen Recognition by the Innate Immune System." International Reviews of Immunology,Vol.30,No.1 (2011): 16-34. Mantovani, Alberto, et al. "Neutrophils in the activation and regulation of innate and adaptive immunity." Nature Reviews Immunology 11 (2011): 519-531. Minnicozzi, Michael, Richard T. Sawyer and Matthew J. Fenton. "Innate immunity in allergic disease." Immunological Reviews, Vol. 242 (2011): 106–127. Porth, Carol . Essentials of Pathophysiology: Concepts of Altered Health States, 3ed. Philadelphia, PA: Lippincott Williams & Wilkins, 2011.Print Rock, Kenneth L., Jiann-Jyh Lai and Hajime Kono. "Innate and adaptive immune responses to cell death." Immunological Reviews Vol. 243, Iss. 1 (2011): 191-205. Takeuchi, Osamu and Shizuo Akira. "Innate immunity to virus infection." Immunological Reviews, Vol. 227 (2009): 75–86. Twycross, Jamie. Integrated Innate and Adaptive Artificial Immune Systems Applied to Process Anomaly Detection. PhD Thesis. Nottingham: University of Nottingham, 2007. Ygberg, Sofia and Anna Nilsson. "The developing immune system – from foetus to toddler." Acta Pædiatrica 101 (2012): 120–127. Read More