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The study of the molecular and cellular components that form the immune system, including their function and interaction, is the central science of immunology. The immune system is divided into a more primitive innate immune system and an acquired or adaptive immune system of vertebrates , each of which contain both humoral and cellular immune ...
Antibodies are major components of humoral immunity. IgG is the main type of antibody found in blood and extracellular fluid, allowing it to control infection of body tissues. By binding many kinds of pathogens such as viruses, bacteria, and fungi, IgG protects the body from infection. [citation needed]
Each antibody binds to a specific antigen in a highly specific interaction analogous to a lock and key.. An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that cause disease.
Each lineage of B cell expresses a different antibody, so the complete set of B cell antigen receptors represent all the antibodies that the body can manufacture. [57] When B or T cells encounter their related antigens they multiply and many "clones" of the cells are produced that target the same antigen. This is called clonal selection. [61]
The descendants are capable of active liberation of soluble antibody and lymphocytes, the same functions as the parental forms. [ 5 ] [ 9 ] In 1958, Gustav Nossal and Joshua Lederberg showed that one B cell always produces only one antibody, which was the first direct evidence supporting the clonal selection theory.
Neutralizing antibodies on the other hand can neutralize the biological effects of the antigen without a need for immune cells. In some cases, non-neutralizing antibodies, or an insufficient amount of neutralizing antibodies binding to viral particles, can be utilized by some species of virus to facilitate uptake into their host cells.
In immunology, an Fc receptor is a protein found on the surface of certain cells – including, among others, B lymphocytes, follicular dendritic cells, natural killer cells, macrophages, neutrophils, eosinophils, basophils, human platelets, and mast cells – that contribute to the protective functions of the immune system.
The process by which the pathogen is introduced into the body is known as inoculation, [note 1] [6] and the organism it affects is known as a biological host. When the pathogen establishes itself in a step known as colonization , [ 7 ] it can result in an infection , [ 7 ] consequently harming the host directly or through the harmful substances ...