IgM is an important component in the first line of defense against foreign pathogens, but may also play a role in autoimmune diseases. IgM monomers consist of two light and two heavy chains. Unlike the heavy chain of an IgG antibody which contains 3 constant Ig domains, the µ heavy chain of IgM contains 4 constant Ig domains. Five IgM monomers complex with a small polypeptide (J-chain) to form pentameric IgM that can be found in human plasma. In an immune response, the binding of IgM to a cell surface antigen enables C1q to activate interactions with downstream components in the classical complement pathway. Mature B lymphocytes express IgM. The G20-127 monoclonal antibody binds to the heavy chain of human IgM. The G20-127 antibody is not thought to react with other immunoglobulin heavy chain isotypes.
The antibody was conjugated to BD Horizon™ BV711 which is part of the BD Horizon Brilliant™ Violet family of dyes. This dye is a tandem fluorochrome of BD Horizon BV421 with an Ex Max of 405-nm and an acceptor dye with an Em Max at 711-nm. BD Horizon BV711 can be excited by the violet laser and detected in a filter used to detect Cy™5.5 / Alexa Fluor® 700-like dyes (eg, 712/20-nm filter). Due to the excitation and emission characteristics of the acceptor dye, there may be moderate spillover into the Alexa Fluor® 700 and PerCP-Cy5.5 detectors. However, the spillover can be corrected through compensation as with any other dye combination.