Table 1.

Comparative binding activities of gammaglobulin (GG), S-sulfonated gammaglobulin (SGG) and S-alkylated gammaglobulin (AGG) for different Fcγ receptors

	EC50 (nM)
Preparation	FcγRIA	FcγRIIA	FcγRIIB	FcγRIIIA	A/I ratio
GG	0·31	60	270	12	23
SGG	2·8	39	92	300	0·31
AGG	2·2	79	92	320	0·29

The activity [effective concentration (EC₅₀)] was calculated by measuring the immunoglobulin G (IgG) concentrations that gave 50% of the maximum binding values, based on the results shown in Fig. 3. A/I ratios were calculated by dividing the EC₅₀ for Fcγ receptor IIB (FcγRIIB) by the EC₅₀ for FcγRIIIA.