Biological Sciences
Immune System
The immune system is a complex network of cells, tissues, and organs that work together to defend the body against harmful pathogens, such as bacteria, viruses, and parasites. It recognizes and responds to foreign substances, producing an immune response to neutralize and eliminate them. The immune system also has memory, allowing it to recognize and respond more effectively to previously encountered threats.
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11 Key excerpts on "Immune System"
eBook - PDFImmunological Computation
Theory and Applications
- Dipankar Dasgupta, Fernando Nino(Authors)
- 2008(Publication Date)
- Auerbach Publications(Publisher)
1 Chapter 1 Immunology Basics In medicine, historically, the term “immunity” refers to the condition in which an organism can resist diseases, more specifically infectious diseases. However, a broader definition of immunity is the reaction to foreign substances (pathogens), which includes primary and secondary immune responses. Mammals have developed a robust defense system called the Immune System to deal with foreign and potentially dangerous pathogens. The Immune System consists of a set of organs, cells, and molecules; and their coordinated response in the presence of a pathogen is known as the immune response . In a broader sense, the physiological function of the Immune System is to defend an organism against all kinds of harmful substances such as fungi, bacteria, parasites, viruses, and other protozoa. However, noninfectious external substances can also generate immune responses (Abbas and Lichtman, 2005). In general, antigens are capable of inducing an immune response as they are assumed to be harmful nonself invaders in the body. The ability of an antigen to induce an immune response probably depends on four main factors: foreignness, molecular size, chemical composition and heterogeneity, and susceptibility to anti-gen processing and antigen presentation. The biological Immune System (BIS) has the ability to detect foreign substances, and to respond adequately. It is inherently distributed and fault-tolerant, and exhib-its a complex behavior while interacting with all its constituents. One of the main capabilities of the Immune System is to distinguish own body cells from foreign substances, which is called self/nonself discrimination . In general, the BIS is capable of recognizing the dangerous elements and deciding an appropriate response while tolerating self-molecules and ignoring many harmless substances.
- Paul Bass, Susan Burroughs, Norman Carr, Claire Way(Authors)
- 2008(Publication Date)
- Churchill Livingstone(Publisher)
Chapter 7. The Immune System 17.1 Natural defences and immunity567.2 Humoral immunity587.3 Cellular immunity617.4 Other components of the immune response63Self-assessment: questions65Self-assessment: answers67Chapter overviewThe study of the Immune System, immunology, is one of the most rapidly expanding and important areas of medicine. Immune mechanisms are involved in a wide range of processes, from inflammation to neoplasia. Diseases due to abnormalities of the Immune System, e.g. acquired immune deficiency syndrome (AIDS) and autoimmune diseases, are encountered in virtually every branch of medicine.7.1. Natural defences and immunity
Learning objectivesYou should:• distinguish innate from adaptive immunity • name the cells important in innate and adaptive immunity and their main properties • describe the morphological organisation of the Immune System • discuss the principles of specificity, memory, diversity and self-recognition.The human body is constantly bombarded from the outside world by potentially harmful substances and microorganisms. To protect ourselves against these insults, we have evolved a sophisticated defence system composed of a complex web of cells and chemical mediators that interact to produce an integrated response. The defences can be divided into two main types:• innate immunity – which has a general protective effect against a wide range of potential insults • adaptive immunity – which is specific for particular foreign substances and microorganisms.Together, the two arms of the Immune System use a wide variety of different methods to distinguish between the components of the body, or ‘self’, from foreign invaders, or ‘non-self’. Non-self includes unacceptable changes within the body, such as a normal cell becoming neoplastic.Many different cells take part in host defence; some are involved only in adaptive immune reactions whereas others play a part in innate immunity as well. The characteristics of some of these cells are discussed further in Chapter 9
- Ian Peate, Muralitharan Nair, Professor Ian Peate, OBE, Professor Muralitharan Nair, Ian Peate, Muralitharan Nair(Authors)
- 2011(Publication Date)
- Wiley-Blackwell(Publisher)
The body is constantly under attack from organisms out to destroy it. This may sound dramatic, but it is true. Infectious micro-organisms, toxins and pollutants are some of the harmful substances from which it has to defend itself. Fortunately, the body has evolved and developed many defences to repel and destroy these harmful substances.Immunology – the study of the Immune System – is a relatively new branch of bioscience and medicine. Although some of the mechanisms and components of immunity, such as antibodies and blood cells, have been known for some time, it is only recently that so much research has been undertaken into the Immune System.Without a doubt, the onset of HIV and AIDS in the 1980s was the trigger for much of this research, and it is now accepted that the Immune System is a complicated and wonderful system which underpins so much of the understanding of disease and disease process, and not only those diseases caused by infectious micro-organisms.This chapter will show what the body’s acquired and innate immune defences consist of and how they work together to give the body a good chance of surviving the continuous and continuing assaults by micro-organisms, toxins and other pollutants, to which it is subjected.Blood cell developmentAll our blood cells are descended from a particular type of cell known as the multipotent stem cell. This multipotent stem cell
eBook - ePubThe Theory of Endobiogeny
Volume 2: Foundational Concepts for Treatment of Common Clinical Conditions
- Kamyar M. Hedayat, Jean-Claude Lapraz(Authors)
- 2019(Publication Date)
- Academic Press(Publisher)
1 Finally, they must be open to the egress of metabolic waste. To be alive is to be open. To be open is to risk one’s integrity. To risk one’s integrity is to risk death. To be alive, ergo, means to risk death. In safeguarding its material constitution, the organism must maintain some mechanism by which it can interact with the external world. That mechanism is the Immune System—generated, mobilized, and regulated by the neuroendocrine system.Immune System: Definition and general function
The Immune System is described as a physiologic system of resistance. The term “immune,” derived from the Latin “in ” and “-munia ,” means “not obligated to service.” Male Roman citizens were obliged to engage in certain duties related to the state. Those who were immune were exempt from this service. To be immune, then, means to be free of what is considered to be a natural consequence of belonging to something larger than oneself. For the individual organism, to be part of the universal expression of Life is to be subjected to the potential for harm, for one cannot survive without being open. Thus, immunity is the state of being free of the natural consequences of being open. Thus, the Immune System is a system of protection more than resistance. More accurately, it is a manager of self vs nonself, of friend vs foe. From this perspective, we see that there are four basic roles of the Immune System: vigilance, tolerance, defense, and attack.Vigilance
Vigilance is by far the most important function of the Immune System. Being aware of the possibility of risk and avoiding harm is far more prudent that reacting to it. Vigilance requires a system of surveillance, a hierarchization of values, and a means to meet a threat. The highest level of surveillance is maintained by the nervous system. It calibrates the threshold of reactivity of the Immune System within the larger context of global functioning via the limbic area. This is why elevated sympathetic tone is implicated in autoimmune disorders from Hashimoto’s thyroiditis to ulcerative colitis, and hyperimmune disorders such as asthma.
eBook - PDFBiological Response Modifiers
New Approaches to Disease Intervention
- Paul Torrence(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
2 Basic Concepts of Immunity MARGARET I. JOHNSTON Department of Biochemistry Uniformed Services University of the Health Sciences Bethesda, Maryland I. Introduction 21 A. Historical Perspective 21 B. Humoral versus Cellular Immunity 22 II. Cellular Participants in the Immune System 24 A. Lymphocytes 24 B. Null Cells 30 C. Monocytes-Macrophages 32 D. Introduction to Major Histocompatibility Antigens 34 E. Other Circulating Cells 36 III. Basic Characteristics of the Immune Response 38 IV. Lymphocyte Subpopulations 40 A. T- and B-Cell Cooperation 40 B. T-Cell Subpopulations 40 C. B-Cell Subsets 42 V. Mechanisms of Cell-Cell Communication and Immune Regulation 42 A. Antigen Bridge Model 42 B. Idiotype Recognition , 43 C. Antigen-Specific Factors 44 D. Antigen-Nonspecific Factors 44 VI. Immune Regulation 48 A. The Jerne Hypothesis 48 B. Suppressor T-Cell Circuits 49 C. Other Potential Regulatory Mechanisms 50 D. Tolerance 50 VII. Importance of the MHC Proteins 51 VIII. Summary 53 References 55 I. INTRODUCTION A. Historical Perspective This volume describes several soluble factors that modify biological re-sponses. Many of these so-called biological response modifiers are pro-BIOLOGICAL RESPONSE MODIFIERS 2 1 Copyright © 1985 by Academic Press, Inc. All rights of reproduction in any form reserved. 22 Margaret I. Johnston duced by and/or act on cells that function in the Immune System. The purpose of this chapter is to introduce the cells and the activities of the cells that participate in immune reactions, with emphasis on cell-cell commu-nication and regulatory mechanisms, so that scientists without a formal background in immunology can put the pages that follow in proper per-spective. Unraveling the mysteries of the immune process began centuries ago, and any author would be hard pressed to point to a beginning of immunology. However, the work of Edward Jenner in the late 1790s is often cited as one of the earliest landmarks in the study of our defense against disease.
eBook - ePub- Nicoladie Tam(Author)
- 0(Publication Date)
- Nicoladie Tam, Ph.D.(Publisher)
Immune System
Objectives- Understand the functions of the Immune System
- Understand the regulation of the Immune System
- Lines of defense
- Specific and non-specific defense
- Phagocyte
- Natural killer cell
- Anti-microbial protein
- Complement protein
- Interferon
- Inflammatory response and histamine
- Allergy
- Virus
- Antigen and antibody
- Characteristics of antibody
- Active and passive immunity
- Vaccine
- Humoral and cell-mediated immunity
- B-cell and T-cell
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TC cell and TH cell
- HIV and AIDS
- Autoimmune disorders
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1.1.Functions of Immune System
Objectives- Understand the role of defense by the immune system
- Lymphatic system and lymphatic nodes
- Immune response to defend the organism
The Immune System and pathogens are co-evolved together, each gets more and more sophisticated in the process. In fact, the Immune System can be considered as the defense system like the military, and the pathogens are the intruders.What is the lymphatic system? It is continuous with the circulatory system, except that it does not contain red blood cells.Lymphatic system is an extension of the circulatory system, and is separate from the circulatory system. It has separate lymphatic vessels, similar to the blood vessels, where lymphatic fluid is found.What is the difference between the lymphatic system and circulatory system? There are lymphatic nodes in the lymphatic system, whereas there is a heart in the circulatory system. The rate of flow in the lymphatic system is much slower than the circulatory system. The lymphatic nodes are distributed in multiple places in the lymphatic system. The flow of lymphatic fluid is very slow compared to the blood flow. Lymphatic fluid eventually drains back into the circulatory system.
- Michael Kennamer(Author)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 48 CHAPTER 4 The Immune Response Learning Objective 4.3 Explain how the Immune System responds to pathogens entering the body. Key Terms: lymphocytes, nonspecific immunity, specific immunity When pathogens enter the body, the Immune System responds. Immunity typically falls into one of two categories. Specific immunity uses lymphocytes (T cells and B cells) to provide protection against specific pathogens. Nonspecific immunity uses neutrophils, macrophages, monocytes, and natural killer cells as a more general defense against pathogens. A description of each type of immunity follows. 1. Which type of immunity uses lymphocytes to provide protection against specific pathogens? a. Nonspecific immunity b. Macrophages c. Autoimmune d. Specific immunity 2. Which type of immunity utilizes natural killer cells? a. Nonspecific immunity b. Macrophages c. Autoimmune d. Specific immunity Knowledge Check 4.3 2. What term is used to describe what occurs when the Immune System erroneously reacts to any part of the body that it perceives as foreign? a. Cancer b. Tumor c. Fever d. Autoimmune Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The Immune System UNDER THE MICROSCOPE ● Interview someone you know who has an autoimmune disease. Seek to discover the obstacles they face on a daily basis. ● Search the literature to learn about other famous people who have (or had) an autoimmune disease.
No longer available |Learn more- Michael Gleeson, Nicolette Bishop, Neil Walsh, Michael Gleeson, Nicolette Bishop, Neil Walsh(Authors)
- 2013(Publication Date)
- Routledge(Publisher)
59 MICHAEL GLEESON AND JOS BOSCH CONClUDING NOTE This overview of the Immune System and the factors affecting it has been given to facilitate the discussions in the chapters that follow on measurement of Immune System status and the effects of acute and chronic exercise on immune function. In some pi aces it has been greatly simplified and the complexity of the Immune System and its precise coordinated responses should not be underestimated. For further details, the interested reader is recommended to consult the excellent textbooks listed under 'Further reading' at the end of this chapter. You can test your understanding of this chapter by performing the activity described in Group Activity 2.2 . Group aetivity 2.2 Check your understanding 01 the organisation 01 the Immune System 60 Th e pr ob lem 1. Fit the following terms into the diagram below: • adaptive immunity • antibody • B lymphocyte • basophil • dendritic cell • eosinophil • granulocytes • immunoglobulin (Ig) • interferon-gamma (IFN-y) • interleukin 2 (IL-2) • interleukin 4 (IL-4) • interleukin 5 (IL-5) • interleukin 13 (lL-13) • macrophage (2 places) • • • monocyte natural immunity natural killer cells • neurrophil • non-specific immunity • plasma cells • specific immuniry • T hel per cell (Th) • T lymphocyte • T suppressorlcytotoxic cell (Tcls) • type-1 T cell (Th 1) • type-2 T cell (Th2) THE HUMAN Immune System 2. In a different colour, circle the phagocytic cells. 3. In anorher colour, circle rhe Iymphocyres. 4. Finally, pur the following c1usrer of differentiation (cluster designaror) nexr ro the corresponding cell type on your diagram: CD3+ CD4+ CD8+ CDI9+ CD56+ KEY POINTS • The Immune System protects against, recognises, attacks and destroys micro- organisms, cells and cell-parts that are foreign to the body (i.e. non-self). It can be broadly divided into two subsystems, the innate (non-specific, natural) and the acquired (adaptive, specific) Immune Systems.
eBook - ePubExploring Immunology
Concepts and Evidence
- Gordon MacPherson, Jon Austyn(Authors)
- 2013(Publication Date)
- Wiley-Blackwell(Publisher)
Finally, of course, nothing could happen without molecules. Some key molecules of immunity are considered in the next section.1.5 Molecular Basis of Immunity
The primary function of the Immune System is to eliminate infectious agents that have breached the natural defences. This is brought about by the integrated actions of different cells and molecules that, directly or indirectly, lead to their elimination. Having outlined the cells of immunity, we now examine the molecular basis of immunity. We describe in a little more detail some of the molecules mentioned above, and introduce others that also play key roles in immunity.1.5.1 Cell-Associated and Soluble Molecules of Immunity
Some of the most important classes of molecules expressed by immune cells are those with the following functions:i. Controlling the positioning of immune cells within the body; for example, they enable these cells to localize within normal tissues or to reach the sites of infection.ii. Enabling the recognition of infectious agents and other signals, so that the cell can make an appropriate response.iii. Communicating with other cells in the vicinity or in more distant tissues, to help bring about a coordinated response.iv. Directly or indirectly acting as effector molecules; for example, by helping to kill the infectious agent (inside or outside of cells) or to kill the cells that may harbour infectious agents (cellular cytotoxicity).In addition, many cell-associated molecules, which include receptors for soluble molecules, are linked to intracellular signalling cascades that frequently lead to changes in gene expression or other cellular functions that are needed in specific responses.Many molecules involved in immunity belong to different superfamilies in which there is a common underlying structure, although functions of the family members may differ widely. For example, molecules of the immunoglobulin superfamily contain different numbers of so-called immunoglobulin domains possessing a characteristic structure. For the purposes of this introduction we will, however, use function to group the molecules of immunity into six main types (Figure 1.20
eBook - PDF- Craig Freudenrich, Gerard J. Tortora(Authors)
- 2011(Publication Date)
- Wiley(Publisher)
The second line of nonspecific innate defense includes internal defenses such as antimicrobialsubstances, macrophages, natural killer cells, inflammation (as shown at right), and fever. The lymphatic system also has the ability to adapt to specific pathogens through adaptiveimmunity. • As shown below, adaptive immunity is of two types: cell- mediatedimmunity and antibody-mediatedimmunity. In cell-mediated immunity, T cells kill infected cells in tissues and release pathogens for subsequent phagocytosis. In antibody-mediated immunity, B cells differentiate to form plasma cells that secrete antibodies, which attack various pathogens. Antibody-mediated immunity occurs mostly in blood and fluids. • In adaptive immunity, various cells present specific antigens to helper Tcells and Bcells that contain receptors for those antigens. These cells undergo clonalactivation, where they proliferate and differentiate into active effector cells and memory cells. Helper T cells then activate cytotoxic T cells to undergo clonal selection. Cytotoxic T cells attack and kill infected cells (cell-mediated immunity). Plasma cells, which are derived from B cells, secrete antibodies (antibody- mediated immunity). • Memory cells help the lymphatic system react more strongly and quickly when your body is subsequently reexposed to any given antigen. This immunological memory is the basis for vaccination. • Activeimmunity produces antibodies following exposure to an antigen, while passiveimmunity supplies antibodies from another source without a full immune response. Passive immunity is temporary, but active immunity can last for decades.
eBook - ePub- Nessar Ahmed, Chris Smith, Maureen Dawson, Ed Wood(Authors)
- 2007(Publication Date)
- Taylor & Francis(Publisher)
Alfred is a 70-year-old man who is suspected of having a myeloma, that is a plasma cell tumor. Suggest tests which could be carried out to confirm the diagnosis. Assuming the plasma cell was producing IgG, suggest an assay which could be used to measure the level of IgG in his blood.4.7 SUMMARY
The basis of the actions of the Immune System is its ability to distinguish self from nonself. It defends the body in a variety of nonspecific and specific ways. Nonspecific defenses include structural barriers and complement. Specific defenses are the development of immune responses against infectious agents. An effective immune response results from the complex interaction of nonspecific and specific cells. The nonspecific cells include the monocytes, large granular lymphocytes and polymorphonuclear leukocytes found in the blood. The specific cells are the small lymphocytes found in the blood and lymphoid tissues. Nonspecific responses include inflammation and the acute phase response, while specific responses include the production of antibodies, known as humoral immunity, and the production of cytotoxic cells, in the process known as cell-mediated immunity. Humoral immunity is effective at dealing with extracellular bacteria and multicellular parasites, while cell-mediated immunity is effective at killing cells infected with a virus. Small lymphocytes are highly specific since they bear cell surface receptors for epitopes found on foreign proteins. Small lymphocytes belong to one of two major subsets, the B lymphocytes responsible for humoral immunity and the T lymphocytes, some of which, the TC cells, can develop into cytotoxic cells, while others, the TH cells, regulate immune responses through the secretion of cytokines.Antibodies are glycoproteins which are highly specific for epitopes. This specificity has enabled them to be used in the detection and quantitation of antigens, in highly sensitive techniques such as ELISA.
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