Definition of antibody

Tim Vickers / Wikimedia Commons / Public Domain In doing so, the antibody effectively marks the pathogen for neutralization, either by killing it or preventing it from entering a healthy cell, or by signalling other complementary proteins to surround and devour the invader in a process called phagocytosis (from the Ancient Greek word for "to devour" [phagein] and "cell" [kytos]). Antibodies are produced by white blood cells called B-lymphocytes, or B-cells. During the prenatal (before birth) and neonatal (newborn) stages of life, antibodies are passed from the mother to the infant through a process called passive immunization. From there, the child will begin to independently produce antibodies, either in response to a specific antigen (adaptive immunity) or as part of the body's natural immune response (innate immunity). Humans are capable of producing over 10 billion types of antibodies, each defending against a specific type of antigen. The antigen-binding site on the antibody called the paratope is located at the tips of the "Y" and locks onto a complementary site on the antigen called the epitope. The high variability of the paratope allows the immune system to recognize an equally wide variety of antigens.

• العربية • Català • Čeština • Dansk • Deutsch • Ελληνικά • Español • Euskara • فارسی • Français • Galego • 한국어 • Bahasa Indonesia • Italiano • Latina • മലയാളം • Nederlands • 日本語 • Norsk bokmål • Oʻzbekcha / ўзбекча • Polski • Português • Русский • Српски / srpski • Srpskohrvatski / српскохрватски • Suomi • Svenska • ไทย • Українська • 中文 Immunoglobulin G ( Ig G) is a It is the most common antibody. Function [ ] Antibodies are major components of [ citation needed] It does this through several mechanisms: [ citation needed] • IgG-mediated binding of pathogens causes their immobilization and binding together via • IgG activates all the • IgG also binds and • IgG also plays an important role in • IgG is also associated with type II and type III IgG antibodies are generated following IgG is secreted as a monomer that is small in size allowing it to easily [ citation needed] Therefore, in the first six months of life, the newborn has the same antibodies as the mother and the child can defend itself against all the pathogens that the mother encountered in her life (even if only through vaccination) until these antibodies are degraded. This repertoire of immunoglobulins is crucial for the newborns who are very sensitive to infections, especially within the respiratory and digestive systems. [ citation needed] IgG are also involved in the regulation of allergic reactions. According to Finkelman, there are two pathways of systemic IgG antibodies can prevent IgE mediated anaphylaxi...

Guide to the structural components that make up an antibody - heavy chains, light chains, F(ab)/Fc regions - and antibody isotypes. Updated May 9, 2022. Antibody structure Antibodies, also known as immunoglobulins (Ig), are large, Y-shaped glycoproteins produced by B-cells as a primary immune defense. Antibodies specifically bind unique pathogen moleculescalled Antibodies exist as one or more copies of a Y-shaped unit composed of four polypeptide chains (Fig. 1). Each Y unit contains two identical copies of a heavy chain (H) and two identical copies of a light chain (L); heavy and light chains differ in their sequence and length. The top of the Y shape contains the variable region (V), also known as the fragment antigen-binding (F(ab)) region. This region binds tightly to a specific part of an antigen called an epitope. The antibody base consists of constant domains (C) and forms the fragment crystallizable region (Fc). This region is essential for the function of the antibody during an immune response. Antibodies exist as one or more copies of a Y-shaped unit composed of four polypeptide chains (Fig. 1). Each Y unit contains two identical copies of a heavy chain (H) and two identical copies of a light chain (L); heavy and light chains differ in their sequence and length. The top of the Y shape contains the variable region (V), also known as the fragment antigen-binding (F(ab)) region. This region binds tightly to a specific part of an antigen called an epitope. Figure 1.A...

Any of numerous Y-shaped glycoproteins that bind to specific antigens and either neutralize them or cause them to be destroyed by other elements of the immune system, such as phagocytes, cytotoxic cells, or complement proteins. Antibodies occur as antigen receptors on the surface of B cells and are secreted as soluble proteins when the B cells mature into plasma cells. Antibodies are also called "immunoglobulins." Did You Know? Antibodies are complex, Y-shaped protein molecules that guard our bodies against diseases. The immune system's B lymphocytes, or B cells, develop into plasma cells, which can produce a huge variety of antibodies, each one capable of grabbing an invading molecule at the top ends of the Y. The molecules that antibodies recognize can be quite specific—they might exist only on a particular bacterium or virus. When that bacterium or virus enters the body, the antibodies quickly recognize its molecules, as if a sentry recognized an enemy soldier from his uniform. Once the invader is caught, the antibodies may make it inactive or lead it to cells that can destroy it. High numbers of a particular antibody may persist for months after an invasion. The numbers may then get quite small, but the experienced B cells can quickly make more of that specific antibody if necessary. Vaccines work by training B cells to do just that. United States of America, Represented by the Secretary, Department of Health and Human Services (Washington, DC) and Scripps Research Ins...

Term Meaning Pathogen A disease-causing organism, including bacteria, Antigen Molecule that stimulates an immune response Innate immune system Non-specific immune system Adaptive immune system Antigen-specific immune system Antibody Specialized Y-shaped protein that tags antigens for destruction B cells White blood cells that produce antibodies and aid in immunological memory T cells White blood cells specialized to assist B cells (helper T) and others directly kills infected cells (killer T) Humoral immunity Adaptive immune defense depending on the action of antibodies Cell-mediated Immunity Adaptive immune defense in which foreign cells are destroyed by T cells Virus Nonliving particle containing protein and DNA/RNA that can infect a living cell Vaccine A killed or weakened form of a pathogen that produces immunity when injected into the body An inflammatory response begins when a pathogen stimulates an increase in blood flow to the infected area. Blood vessels in that area expand, and white blood cells leak from the vessels to invade the infected tissue. These white blood cells, called phagocytes engulf and destroy bacteria. The area often becomes red, swollen, and painful during an inflammatory response. Specific immune responses are triggered by antigens. Antigens are usually found on the surface of pathogens and are unique to that particular pathogen. The immune system responds to antigens by producing cells that directly attack the pathogen, or by producing special ...

Autoimmunity is very common If we use autoantibodies as an indicator for autoimmunity, we find there are many, many types of autoantibodies, directed against many different self-antigens. Thus, it is not surprising that if we were to test the serum broadly enough, we would find some autoantibodies in most “healthy” individuals. Similar reasoning applies to autoreactive T cells, although in the clinical laboratory it is much more complicated to test for T cells than for autoantibodies. An additional proof that autoantibodies and autoreactive T cells can be present in individuals who do not have clinical evidence of autoimmune disease comes from the new types of cancer treatment based on immunotherapy. Cancer patients who are treated with Prevalence of ANA in the general population by age and gender (Guo YP et al Curr Ther Res, 2014). Autoantibodies are an excellent biomarker for autoimmunity Since the beginning of the autoimmunity field, autoantibodies have been the tool used by clinical laboratories to diagnose and monitor autoimmunity. There are literally hundreds of different autoantibody tests a physician can order nowadays. The most common autoantibody test is the so-called ANA (for anti-nuclear antibody), which is performed using a technique called ANAs are often found in the general population, even in the absence of any autoimmune disease. As the line graph shows, the prevalence of ANAs in the general population increases with age, and it is higher in women than men...