IVIG pharmacokinetics. IVIG was administered by intraperitoneal injection at doses of 0.4 g/kg (▪), 1 g/kg (♦), and 2 g/kg (▴). IVIG was injected 96 hours after initiation of the MWReg30 infusion. IVIG concentrations in plasma were assessed via ELISA and were found to increase with dose. Systemic clearance, assessed by the ratio of IVIG dose to the area under the mean IVIG plasma concentration versus time curve, was found to increase with increasing doses of IVIG. This finding is consistent with the hypothesis that high-dose IVIG therapy leads to inhibition of the IgG transporter FcRn. Error bars indicate the standard deviation of assayed IVIG concentrations.