Table 2 Affinity constants of human IgG... | American Society of Hematology

Table 2

Affinity constants of human IgG receptors for human IgG subclasses (× 10⁵M⁻¹)¹⁸

	FcγRI	FcγRIIA		FcγRIIB	FcγRIIC	FcγRIIIA		FcγRIIIB	FcRn
	FcγRI	H₁₃₁	R₁₃₁	FcγRIIB	FcγRIIC	V₁₅₈	F₁₅₈	NA1,NA2,SH	FcRn
IgG1	650*	52	35	1.2	1.2	20	11.7	2.0	80*
IgG2	—	4.5	1.0	0.2	0.2	0.7	0.3	—	NA
IgG3	610*	8.9	9.1	1.7	1.7	98*	77	10	NA
IgG4	340*	1.7	2.1	2.0	2.0	2.5	2.0	—	NA

	FcγRI	FcγRIIA		FcγRIIB	FcγRIIC	FcγRIIIA		FcγRIIIB	FcRn
	FcγRI	H₁₃₁	R₁₃₁	FcγRIIB	FcγRIIC	V₁₅₈	F₁₅₈	NA1,NA2,SH	FcRn
IgG1	650*	52	35	1.2	1.2	20	11.7	2.0	80*
IgG2	—	4.5	1.0	0.2	0.2	0.7	0.3	—	NA
IgG3	610*	8.9	9.1	1.7	1.7	98*	77	10	NA
IgG4	340*	1.7	2.1	2.0	2.0	2.5	2.0	—	NA

— indicates no binding; and NA, not analyzed.

High-affinity binding.