Table 2 Properties of human IgG subclasses and relative binding affinity with major FcγRs [26, 27]

Molecular mass (kD)

146

146

170

146

Amino acids in hinge region

15

12

62

12

Inter-heavy chain disulfide bonds

2

4

11

2

Complement activation (C1q binding)

++

+

+++

—

FcγRI

650

—

610

340

FcγRIIa-H131

52

4.5

8.9

1.7

FcγRIIa-R131

35

1

9.1

2.1

FcγRIIb

1.2

0.2

1.7

2

FcγRIIIa-V158

20

0.7

98

2.5

FcγRIIIa-F158

11.7

0.3

77

2