Salient features of IgG subclasses and how they compare with each other:
Property | IgG1 | IgG2 | IgG3 | IgG4 |
Molecular weight | 150 kDa | 150 kDa | 170 kDa | 150 kDa |
Inter-H chain disulfide bonds | 2 | 4 | 11 | 2 |
Amino acids in hinge region | 15 | 12 | 62 | 12 |
Half-life | 14-21 days | 14-21 days | 7 days | 14-21 days |
% of total IgG | 60-65% | 20-25% | 5-10% | <4% |
Functions | Responsible for thymus-mediated immune response against proteins and polypeptide antigens | Is the prevalent immune response against carbohydrate/protein antigens | Plays a key role in the immune responses against protein or polypeptide antigens | Precise function remains unknown |
Deficiency | Sign of hypogammaglobulinemia | Associated with recurring respiratory infections in infants | - | Associated with cholangitis, interstitial pneumonia and sclerosing pancreatitis |