Figure 4

(A) The competitive effect of IVIg (FLEBOGAMMA) on IgG/IgM binding of pooled human serum to WT/GTKO pRBCs. High-dose (40 mg/ml) IVIg attenuated human serum IgG binding (but not IgM binding) to WT pRBCs (p < 0.01). IVIg increased human serum IgG binding to GTKO pRBCs, and increased IgM binding to both WT and GTKO pRBCs. See “Materials and methods” section (Competitive binding to pRBCs of IVIg with IgG and IgM from pooled human serum). Heat-inactivated serum was used in this assay. On the y axis, the dotted line represents the lowest measurable limit of binding, below which there is considered to be no binding (relative GM: IgM 1.2, IgG 1.1). Results are expressed as mean + /− SD (**p < 0.01). (B) The competitive effects of IVIg (FLEBOGAMMA) on IgG/IgM binding of pooled human serum to WT/GTKO pAECs. IVIg did not attenuate human serum IgG binding to either WT or GTKO pAECs and increased IgM binding. There was no IgG binding of pooled human serum or IVIg to GTKO pAECs. See “Materials and methods” section (Competitive binding to pAECs of IVIg with IgG and IgM from pooled human serum). Heat-inactivated serum was used in this assay. On the y axis, the dotted line represents the lowest measurable limit of binding, below which there is considered to be no binding (relative GM: IgM 1.2, IgG 1.1). Results are expressed as mean + /− SD.