Immunoglobulin G (IgG)
IgG is the most common type of , comprising about 80% of the body's total. It is equally divided
between the blood and interstitial fluid. IgG antibodies represent a large vocabulary of
There are four subgroups, currently labeled with number suffixes ( IgG1 to 4 ). In some mucosal tissues
(e.g. mammary glands of ruminants),
the IgG1 class of immunoglobulin-producing cells predominate while IgG4
is the major circulating antibody which enters tissues freely and participates in diverse immune events.
IgG (as well as ) activates the complement system.