This chapter provides a background on how the body keeps infections at bay. It explores the two major branches of the immune system (the innate immune system and the adaptive immune system) and the cells, molecules, and tissues that drive their responses to provide protection from infectious disease. It also reviews a vast array of mechanisms that the human body relies on to keep them healthy in spite of all the challenges the immune system faces daily. The chapter explains immunology as the study of immunity from diseases and the mechanisms used by the immune system to provide protection against pathogens. It explains that pathogens have the ability to cause disease, either via bacteria, viruses, fungi, protozoa, or parasites.
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Introduction to Immunology and the Immune System
Stephen Juris
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Defence, immunity, the immune system
This chapter outlines the development of a whole new understanding of the causes and effects of infectious disease and how to treat such diseases. It elucidates the two new disciplinesmicrobiology and immunologytogether with the gradual identification of a body wide repertoire of organs, cells, and molecules devoted to controlling infection: the immune system. The chapter also discusses the problem of defence against a pathogen, then demonstrates the three levels of defence: external defences, the innate immune system, and the adaptive immune system. The chapter then highlights that an immune system requires three sets of components to work properly: recognition molecules, disposal mechanisms, and a communication system. Finally, the chapter presents the distinction of the two parts of the immune system: the innate and the adaptive immune systems.
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Basic and laboratory immunology
This chapter explores basic and laboratory immunology. It discusses the key concepts of organs, cells, and humoral components of the immune system. Some degree of immunological and inflammatory process is present in almost all forms of disease. The immune system aims to protect people from microbiological attacks by recognizing anything that is not part of the body and then destroying it. The chapter examines the interplay between immunology and inflammation, and the differences between the innate immune system and the adaptive immune system. It also explains that laboratories are an indispensable part of the diagnosis and management of immunological and inflammatory diseases.
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Introduction to Immune Responses, Cells, Mediators, and Structures
This introductory chapter provides an overview of immune responses, outlining the cells, mediators, and structures of the immune response. The immune system recognizes and destroys things that are dangerous. These are agents or conditions that cause harm to the body. Usually, pathogens first bind body cells to gain entry, and then cause damage in tissue which leads to the activation of signals and the generation of inflammation. In a well-functioning immune system, the signals from the tissues instruct the quantity and the quality of the specific immune responses required to eradicate any danger that is present. The chapter then looks at two integrated systems which work together to eradicate pathogens and limit the development of tumours: innate immunity and adaptive immunity. The key difference between the innate and adaptive immune responses is the way they recognize pathogens (different types of receptors).
Book
Stephen J. Juris
Immunology introduces this discipline, which is a subject containing vast amounts of detail. The immune system is vastly complex. This text tries to unravel the mysteries of immunology through accounts of classical discoveries and recent, cutting-edge research. The text starts with an introduction to the subject. There follows chapters on innate immunity, the complement system, and adaptive immunity. Chapters then cover T Lymphocytes, the development of B Lymphocytes, and B-cell diversity. The text also looks into immunological memory and vaccination, mucosal immunity, and pathogen evasion of the immune system. Immunodeficiencies are covered. As are allergies and hypersensitivity. Autoimmune diseases are the subject of another chapter. The text ends with two chapters looking at transplantation, immune responses to transplantation, and cancer of the immune system.
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The immune system
This chapter focuses on the immune system of animals. This immune system protects against pathogenic invaders, wherein there is an innate immune response in which phagocytes engulf invading pathogens. The chapter explores the adaptive immune response. This responds to macromolecules, mainly proteins and complex polysaccharides, but not to small foreign molecules unless attached to large ones. Foreign macromolecules are indicative of an invader and are called antigens because antibodies are generated in response to them. The chapter includes two arms of the adaptive immune response: the humoral in which antibodies prevent pathogens in the blood and tissue fluids from entering cells and aid their removal from the body, and cell-mediated immunity in which cytotoxic T cells destroy infected cells. Cells of the immune system, known as lymphocytes, recirculate through the blood and lymphoid tissues to the sites of potential infection.
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Anne C. Cunningham
Thrive in Immunology first provides a detailed introduction to immune responses and looks specifically at cells, mediators, and structures and it asks: how is the immune system activated? It then considers what the immune system destroys. Finally, at the end of the text, the last section consider the role of the immune system in health and disease.
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Pathogen Evasion of the Immune System
Stephen Juris
This chapter reviews mechanisms the body uses to combat pathogens and the mechanisms pathogens use to evade immune responses. It highlights the evolutionary arms race between the immune system, which is an efficient weapon against many pathogens that have evolved elaborate mechanisms to survive immune system defenses. It also explains how pathogens use a variety of mechanisms to subvert or evade the immune system hiding from immune system cells, blocking or disrupting the immune response, downregulating immune system activity, and using superantigens to induce a nonspecific immune response. The chapter looks at bacterial pathogens that can reside intracellularly by inducing phagocytosis and then halting the phagocytic process before they are digested by the phagocyte. It also looks at pathogens that can express superantigens that induce a nonspecific lymphocyte response.
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The Complement System
Stephen Juris
This chapter discusses some of the important components of the innate immune system that act to keep pathogens at bay. It highlights a key component of the innate immune system involving soluble plasma proteins: the complement system. The complement system constitutes a variety of proteins involved in recognizing and tagging foreign molecules and pathogens. The chapter points out how this family of proteins coats the surface of foreign molecules and cells, tagging them to mark them as candidates for destruction by innate immune cells. It explains how the complement system bears a remarkable similarity to the body's blood-clotting system as it involves a cascade of different proteins, each of which must be activated by cleavage via a protease to induce the next step in the process.
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Immune System
This chapter discusses the components and purpose of the immune system. The immune system is designed to recognize and destroy anything dangerous to the body, which includes pathogens and tumour cells. In the absence of a functional immune system, people quickly become sick and die if they do not have the intervention of modern medicine. The chapter explores the differences between innate immunity and adaptive immunity and the subsequent immunodeficiencies that happen when diseases affect the development and function of lymphocytes. It acknowledges vaccination as one of the major medical achievements that can provide lifelong immunity against a range of infectious diseases.
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Immune System
This chapter discusses the components and purpose of the immune system. The immune system is designed to recognize and destroy anything dangerous to the body, which includes pathogens and tumour cells. In the absence of a functional immune system, people quickly become sick and die if they do not have the intervention of modern medicine. The chapter explores the differences between innate immunity and adaptive immunity and the subsequent immunodeficiencies that happen when diseases affect the development and function of lymphocytes. It acknowledges vaccination as one of the major medical achievements that can provide lifelong immunity against a range of infectious diseases.
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Immunodeficiency III: secondary immunodeficiency and AIDS
This chapter concentrates on the defects in secondary immunodeficiencies and its principal causes. It emphasizes that secondary immunodeficiency results from some influence external to the immune system-infection, malnutrition, etc-ranging from the slightly increased risk of infection following surgery to the severe and progressive immune failure of HIV/AIDS. Since most adult immunodeficiency falls into this category, the chapter discusses both innate and adaptive immunity. The chapter also elaborates on other infection which has an effect on the immune system as well as the immunosuppression caused by the other infections. Next, the chapter considers other causes of immunodeficiency, then analyzes the infections in immunodeficient patients.
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Defending against the invaders
This chapter evaluates the defences that make up the human immune system, which are crucial to our ability to fight off infectious diseases. The innate immune system has a variety of defences to prevent pathogens from infiltrating the body. Macrophages such as mast cells, dendritic cells, basophils, and eosinophils aid in recognizing pathogens and chemically signalling to other aspects of the immune system, such as phagocytes, T-cells, and B-cells. The T-cell and B-cell pathways are known as the adaptive immune response, as they are capable of adapting to new pathogens. They also 'remember' antigens, through the use of T and B memory cells, allowing the body to quickly respond to any pathogens that it has encountered before. The chapter then looks at autoimmune disorders, which are caused when the immune system fails to recognize other cells within the body and attacks them in the same way that it attacks pathogens.
Book
Gillian Pocock, Christopher D. Richards, and David A. Richards
Human Physiology provides clear explanations of the principles that govern the body’s physiological processes and shows how these can be applied. It is made up of eleven sections. Section 1 is about basic concepts. The second section covers the organization and basic functions of cells. The third section looks at the excitable tissues, nerve, and muscle. The fourth section goes into detail about the nervous system and special senses. The section which follows is about the endocrine system and it includes details on the pituitary gland, hypothalamus, the thyroid and parathyroid glands, the adrenal gland, and the endocrine pancreas. The text also looks at blood and the immune system, before turning to the cardiovascular and respiratory systems. There follows a section of the regulation of the internal environment. Towards the end the text turns to the gastrointestinal system. Finally, the text looks at reproduction and growth.
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The Role of the Immune System in Health and Disease
This chapter focuses on the role of the immune system in health and disease. A well-functioning immune system should be in balance—it should recognize and destroy those things that cause harm (infectious agents, tumours) but ignore those things which are harmless. However, some individuals have gene defects in immune response genes. These are rare but can help in understanding how the immune system works. Immunodeficient patients are more susceptible to infections, do not necessarily respond to vaccines, and may be more at risk of developing tumours. Immunodeficiency can also lead to autoimmunity—when the immune system attacks the body. Meanwhile, ‘hypersensitivities’ are inflammatory immune responses mediated by adaptive immune responses (i.e. lymphocytes). Transplant rejection is also affected by adaptive immune responses. In contrast, established tumours are anti-inflammatory environments. Immunotherapy aims at inducing adaptive immune responses specific to the tumour.
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Immune regulation, food allergies, and food intolerance
Stephan Strobel and Carina Venter
This chapter details features of the immune system before exploring the relationships between nutrition, immunodeficiencies, and interactions between micronutrient status and immunity. It then discusses major aspects of the immune system and its regulation with particular reference to food allergies and food intolerance. Specific receptors provide interfaces between integrated defence systems and the relationships between innate and adaptive immunity. The chapter considers the effects of malnutrition and obesity to examime the relevance of immune function and public health outcomes. It then examines the nutritional strategies related to the prevention, diagnosis, and management of adverse reactions to food.
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Tumor immunology and immunotherapy
This chapter discusses tumor suppression and tumor promotion mechanisms of the immune system. It notes that the immune system is a network of cells, signals, and organs that helps protect against dangerous pathogens and cancer. The chapter then emphasizes that the immune system plays a dual role in cancer: it has both anti-tumor and pro-tumor effects. On one hand, immune cells can recognize and eliminate tumor cells, including the killing of virus-infected cells. On the other hand, the immune system may exert selective pressure that shapes the antigens displayed by the tumor cells, leading to evasion of the immune system and cancer promotion. The chapter then describes the regulatory mechanisms that are used to control the immune response and factors that play a role in immune evasion. It then concludes by reporting exciting applications of this knowledge towards developing cancer immunotherapies, therapies that are demonstrating unprecedented results.
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Autoimmune Diseases
Stephen Juris
This chapter explores problems that occur when tolerance to self-antigens is lost, noting that cells of the adaptive immune system undergo somatic recombination events to provide a diverse array of receptors at their surfaces. It analyses similarities between autoimmune diseases and hypersensitivity responses. While the antigens recognized in hypersensitivity reactions differ from those recognized in autoimmune, recognition prompts activation of adaptive immune responses that can be damaging and life-threatening. The chapter describes how autoimmune diseases are induced due to a lack of central or peripheral tolerance of the adaptive immune system. It highlights the failure of central and peripheral tolerance, which drives the onset of autoimmune disease and caused by both genetic and environmental factors.
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Innate Immunity
Stephen Juris
This chapter explores the many mechanisms that the innate immune system employs to combat pathogens. It looks at the ways in which the innate immune system uses physical and chemical barriers to stave off infection and how it employs innate immune cells to seek out and destroy pathogens. It also analyzes how the innate immune system uses a variety of effector functions to efficiently clear infections. The chapter covers the action of innate immune cells and the use of soluble signaling molecules which function to increase the effectiveness of the innate immune response and facilitate pathogen destruction. It cites Salmonella as an example of an ingested pathogen that the immune system fights using a variety of physical and chemical barriers.
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Cancer and the Immune System
Stephen Juris
This chapter investigates the interaction of the immune system with cancer cells, noting that cancer are the result of mutations within cells that affect the ability of the body to control the cell cycle and cell division. It considers proto-oncogenes and tumor suppressor genes as two key gene families that work to promote progression through the cell cycle. These are targets for mutations that can lead to the onset of cancer. It also highlights the battle that ensues between cancer cells, which aim to continue to survive and divide, and immune mechanisms, which aim to recognize and target harmful pathogens and cells. The chapter demonstrates how cancer cells avoid destruction by immune system effect or mechanisms by avoiding detection or manipulating the immune response that would normally target these cells. It talks about the recognition of the adaptive immune system of cancer cells through tumor-associated or tumor-specific antigens expressed by these cells.
