What is IgG?

IgG stands for Immunoglobulin. It is the most common type of antibody, comprising about 75% of serum antibodies in humans. Immunoglobulin molecules are generated and released by plasma B cells and are present in the blood and other body fluids. IgG protects against viral and bacterial infections by multiplying and attacking foreign pathogens that invade the body. Infections set in when the body does not have sufficient IgG. There are 4 distinct subclasses IgG1, IgG2, IgG3, and IgG4.