immunoglobulin G2
Last reviewed 01/2018
IgG2 is usually produced in response to a bacterial or viral infection.
IgG2 dominates the antibody response to polysaccharide antigens such as those of Streptococcus pneumoniae and Haemophilus influenzae. Production begins in the second year of life and adult levels of IgG2 are rarely attained before four years of age, accounting for the high incidence of infection with organisms coated with carbohydrate capsules in young children.
The reason a polysaccharide vaccine can be successful in infants - who do not have IgG2 - is the conjugation of the polysaccharide to an antigen such as diphtheria or tetanus toxoid.
IgG2 abscence may be associated with IgA deficiency.