How are the subclasses of immunoglobulin G differentiated?

Question

Accepted Answer

Salient features of IgG subclasses and how they compare with each other:

Property

IgG1

IgG2

IgG3

IgG4

Molecular weight

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

7 days

14-21 days

% of total IgG

60-65%

20-25%

5-10%

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

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