Immunoglobulin G (IgG) is a 150 kDa soluble protein that serves as a major effector molecule of the humoral immune response in man. Its concentration in blood plasma of healthy individuals is approximately 10 g/l, which accounts for about 75% of the total plasma immunoglobulins. IgG has the highest stability of blood immunoglobulins (T1/2 = 21 days) and is able of placental transfer. IgG is secreted by plasma cells at a comparably high rate as other immunoglobulins.
