The immune system protects against infection through various lines of defense. When the immune system does not function properly, it can lead to diseases such as autoimmunity, allergies and cancer. For centuries, leading to safe organ transplants, blood typing, and the ubiquitous use of monoclonal antibodies throughout science and healthcare, immunology has changed the face of modern medicine. Immunology research continues to expand our understanding of how to treat major health problems, with research underway in immunotherapies, autoimmune diseases and vaccines against emerging pathogens such as Ebola. A deeper understanding of basic immunology is critical for clinical and commercial applications and facilitates the discovery of new diagnostics and therapeutics to manage a wide range of diseases.
The immune system is a complex system of structures and processes that have evolved to protect us from disease. Molecular and cellular components make up the immune system. The functions of these components are divided into non-specific mechanisms, that is, mechanisms intrinsic to the organism, and reactive responses adapted to specific pathogens. Basic or classical immunology involves the study of the components that make up the innate and adaptive immune systems.
Innate immunity is the first line of defense and is non-specific. That is, the response is the same to all potential pathogens, no matter how different they may be. Innate immunity includes physical barriers (such as skin, saliva, etc.) and cells (such as macrophages, neutrophils, basophils, mast cells, etc.). These components "ready" and protect the organism during the first days of infection. In some cases, this is enough to remove the pathogen, but in others, the first line of defense is overwhelmed and the second line comes into play.
Adaptive immunity is the second line of defense, which involves building a memory of the infection encountered so that a specific response to the pathogen or foreign substance can be enhanced. Adaptive immunity involves antibodies, which are usually directed against foreign pathogens roaming in the blood. Also involved are T cells, which specifically target pathogens that have colonized cells, either directly killing infected cells or helping to control antibody responses.
The immune system is a highly regulated and balanced system, and when the balance is disturbed, disease can result. Research in this field involves the study of diseases caused by dysfunction of the immune system. Much of this work has important implications for the development of new treatments and therapies that can control or cure disease by changing how the immune system works or, in the case of vaccines, prime the immune system and enhance its defenses against specific pathogens immune response.
Immunodeficiency disorders involve problems with the immune system that impair its ability to mount an appropriate defense. Consequently, these diseases are almost always associated with severe infections that persist, recur, and/or lead to complications, making them severely debilitating and even fatal. There are two types of immunodeficiency disorders: Primary immunodeficiency is usually present from birth, is usually hereditary and is relatively rare. An example of this is common variable immunodeficiency (CVID). Secondary immunodeficiency usually develops later in life and may develop after infection, as in AIDS after HIV infection.
Autoimmune disease occurs when the immune system attacks the body it is supposed to protect. People with autoimmune diseases have a defect that makes them unable to distinguish "self" from "non-self" or "foreign" molecules. Principles of Immunology offers a variety of laboratory tests for detecting autoimmune diseases. Autoimmune diseases can be described as "primary" autoimmune diseases, such as type 1 diabetes, which may manifest at birth or early in life; or as "secondary" autoimmune diseases, due to various factors manifest in later life. Rheumatoid arthritis and multiple sclerosis are considered examples of this type of autoimmunity. In addition, autoimmune diseases can be localized, such as Crohn's disease, which affects the gastrointestinal tract, or systemic, such as systemic lupus erythematosus (SLE).
Allergies are allergic diseases that occur when the body's immune system reacts to a harmless foreign substance, causing damage to the body's own tissues. Allergies (allergens) can be caused by almost any substance, but most commonly, allergies are caused after eating certain types of food (such as peanuts) or inhaling airborne substances (such as pollen or dust). In an allergic reaction, the body perceives the allergens as dangerous and immediately produces substances to attack them. This causes immune system cells to release powerful chemicals, such as histamine, which cause inflammation and many of the symptoms associated with allergies. Immunology is devoted to understanding what happens to the body during an allergic reaction and what causes it.