Immunoglobulin M

The immunoglobulin M (IgM) is an antibody molecule consisting of five Y-shaped sub-units which are joined together at the long ends. The individual antigen-binding molecules carried by additional intermolecular disulfide bonds and the so-called J chain. Its concentration in serum is 1.5 mg / ml.

The basic unit consists of two long ( "heavy", and H - chain (of English heavy) ) and two short ( "light", and L- chain) protein chains and has the shape of a "Y". The binding sites to antigens (foreign bodies, for example, specific surface structures of bacterial cells ) are able to bind to the short ends of the Y.

IgM has a function as the earliest in the course of an immune response produced immunoglobulin for activation of the complement system, which is why an increased IgM antibody level in a blood test on an actual immune response - ie a current infection - suggesting.

Natural IgM

Natural IgM antibodies are secreted by B1 cells. In humans, these CD20 , CD27 , CD43 and CD70 . Apart from their role in the defense against invading microbes they are involved by complement-dependent mechanisms also at the tissue homeostasis through clearance of apoptotic cells and modified. They inhibit the inflammation, remove malformed cells and regulate both the pathogenic autoreactive antibodies of the IgG isotype, and the autoantibody - producing B cells. This opens up in the future possibly new therapeutic options such as the stimulation of the production of natural IgM or the pharmacologic substitution of monoclonal or polyclonal IgM preparations. IgM antibodies are in the ontogeny of the B cells in the first and form the first immunoglobulin isotype that is secreted during the antigen-specific immune response.

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