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Background
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Serum immunoglobulin IgG is the main component, accounting for total serum immunoglobulin content of 75 %. 40 ~ 50 % of the distribution in the serum, and the remaining distributed in the organization. Molecular weight of about 150 kDa. Human serum IgG mainly single, normal, including four subtypes of IgG, IgG1 accounted for its 60 ~ 70 %, IgG2 accounted for 15 ~ 20 %, IgG3 accounted for 5 ~ 10 %, IgG4 accounts for 1 ~ 7 %. These subtypes in the classical pathway of complement activation in the binding capacity varies. IgG mainly by the spleen and lymph nodes in the synthesis of plasma cells, is the only antibodies through the placenta, to prevent birth within weeks of infection play a significant role. Newborn infants after 3 months has been able to synthesize IgG, 2 ~ 3 years old has reached ***** levels. Decreased gradually after the age of 40. IgG content of individual differences, the same individual under different conditions, fluctuations are also high. Antigen stimulation in the body produces most of the anti-bacterial, anti-virus, anti-toxin antibodies are IgG. Many autoantibodies, such as systemic lupus erythematosus LE factor, anti-thyroglobulin antibodies are IgG. IgG is the body's main anti-infection immune antibodies.
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