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Immunoglobulin M (IgM) is the largest of several isotypes of antibodies (also known as immunoglobulin) that are produced by vertebrates.IgM is the first antibody to appear in the response to initial exposure to an antigen; [1] [2] causing it to also be called an acute phase antibody.
The pentameric structure of IgM antibodies makes them efficient at binding antigens with repetitive epitopes (e.g. bacterial capsule, viral capsid) and activation of complement cascade. As IgM antibodies are expressed early in a B cell response, they are rarely highly mutated and have broad antigen reactivity thus providing an early response to ...
Elevated levels of macroglobulins (macroglobulinemia) may cause manifestations of excess blood viscosity (as is the case for IgM antibodies in Waldenström macroglobulinemia) and/or precipitate within blood vessels when temperature drops (as in cryoglobulinaemia).
Subsequent infections will demonstrate similar patterns, with initial IgM peaks and significantly stronger IgG peaks, with the IgG peak occurring more rapidly during subsequent infections. [3] Thus an elevated IgM titre indicates recent primary infection or acute reinfection, while the presence of IgG suggests past infection or immunization.
Immunodeficiency with hyper IgM type 2 is caused by a mutation in the Activation-Induced Cytidine Deaminase gene, which is located on the short arm of chromosome 12.. The protein that is encoded by this gene is called Activation-Induced Cytidine Deaminase (AICDA) and functions as a DNA-editing deaminase that induces somatic hypermutation, class switch recombination, and immunoglobulin gene ...
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.
The cause of selective IgM deficiency remains unclear, although various mechanisms have been proposed, such as an increase in regulatory T cell functions, defective T helper cell functions and impaired terminal differentiation of B lymphocytes into IgM-secreting cells among others. [2]
Other than in rheumatoid arthritis, rheumatoid factor may also be elevated in other conditions, including: Systemic lupus erythematosus (SLE) [14] [15] Sjögren syndrome [14] [15] Hepatitis B and C, [16] herpes, HIV, and other viral infections [15] Primary biliary cirrhosis [15] Infectious mononucleosis and any chronic viral infection [14 ...