Immunoglobulins

Abstract

Immunoglobulins (antibodies) are glycoprotein molecules that play a key role in adaptive immunity. Antibody is a Y shaped molecule made up of four polpeptides-2 heavy chains and 2 light chains. They protect us in the hostile environment of bacteria, viruses, and parasites. There are five classes of human immunoglobulins: IgM, IgG, IgA, IgE, and IgD. Most IgM antibodies are “natural” i.e., they are produced even without an antigenic stimulus. Their antigen-binding polyspecificity ensures them a role as a first line of defence mechanism against invading pathogens. IgG is the most abundant immunoglobulin isotype in human plasma. The ability of IgG antibodies to bind with a high affinity and specificity to a remarkably large variety of antigens is their main feature. It combats microbes and their toxins. Serum IgA has effects similar to these of IgG, while secretory IgA antibodies are resistant to proteases and protect all mucosal surfaces. IgE is the class with the lowest plasma concentration. The contact of mast cell-bound IgE with the specific antigen results in an acute inflammatory reaction that might help to expel parasites from the gut. IgE antibodies are also believed to have a role in the host defense against noxious environmental substances, including venoms, environmental xenobiotics, and irritants IgD is primarily found on surface of mature B cells and is probably involved in lymphocyte activation. An immunoglobulin superfamily of which antibody is a large and diverse group of protein comprising antibodies. Antibodies can swiftly provide therapeutics to target disease-related molecules discovered in genomic research. Antibody engineering techniques have been actively developed and these technological innovations have intensified the development of therapeutic antibodies.