IgG subclass 2
What it measures, and what changes the number.
IgG subclass 2 (IgG2) is one of the four subclasses of immunoglobulin G. It is usually the second most abundant subclass and is especially important in responses to polysaccharide antigens, such as the sugar coatings found on some bacteria.
It is measured together with IgG1, IgG3, IgG4 and total IgG, because the subclasses are read as a group and their sum is compared with total IgG. Total IgA is often measured in the same workup, and vaccine response antibody tests are sometimes read alongside it.
Subclasses are measured by nephelometry or immunoassay, and results can differ between kits and laboratories. Expected values change with age, as IgG2 matures more slowly in young children. Fasting is not usually required. Labs may print it as IgG2, IgG subclass 2 or Inmunoglobulina G subclase 2.
Often read alongside: IgG, IgG subclass 1, IgG subclass 4, IgA