Functions of antibodies/ Antibody functions

#sowmyanagaraj #sowmyanrao #swiminscience Functions of Antibody An antibody has two main parts which are involved in its functions. They are: fragment antigen-binding or Fab fragment and fragment crystallizable region that is Fc region. The Fab fragment is involved in recognizing and binding antigens. The Fc region binds to different immune cell receptors and evoke different effector functions that results in the destruction and removal of the antigens. Different functions of an antibody are: Opsonisation Antibodies (mainly IgG1 and IgG3) can act as opsonins by binding to the pathogen through their paratopes, which allows better recognition by phagocytes. This antibody-antigen complex then binds to phagocytes through their Fc receptors and phagocytosis is initiated to eliminate the pathogen. Neutralisation Antibodies can prevent pathogens from accessing cells by blocking different parts of the bacterial or viral cell surface. Consequently, this neutralises certain viruses and bacterial toxins. IgG and IgA antibodies have the greatest effect. Complement Activation Complement system contains a collection of plasma proteins that work together to fight infection. In a classical complement pathway, a complement protein detects antibodies bound to the surface of a pathogen. This further activates other complement proteins resulting in the formation of the membrane attack complex – a cylindrical structure that is inserted into the cell wall of the pathogen, thus puncturing its membrane. Through this pore, fluids and molecules flow in and out of the cell. The cell swells and bursts. Immune Complexes The binding of multiple antigens and antibodies together can form immune complexes. Complex formation limits the antigens’ diffusing ability, making it easier for phagocytes to find and ingest pathogens through phagocytosis and simultaneous destruction of several pathogens. Antibody-Dependent Cell-Mediated Cytotoxicity Antibodies bind and opsonise target cells such as virus-infected host cells or tumor cells. Effector cells such as Natural killer cells recognize the Fc portion of the antibody and release cytotoxic granules (perforin and granzymes) into the target cell which triggers apoptosis. References: https://www.sinobiological.com/resource/antibody-technical/antibody-structure-function https://byjus.com/biology/antibodies-role-of-antibodies/ https://teachmephysiology.com/immune-system/adaptive-immune-system/antibodies/ Kelly, J., 1992. Immunology: by Janis Kuby, WH Freeman. https://en.wikipedia.org/wiki/Complement_system#/media/File:Complement_pathway.svg https://www.creative-diagnostics.com/complement-system.htm BGM Music track: Thoughtful by Pufino Source: https://freetouse.com/music Free Background Music (No Copyright)