Total C3b-containing complexes in plasma of ADM and DM patients treated with 2 g IVIG/kg body weight. Plasma samples were drawn during IVIG infusion (percent infused IgG is listed during day 1 and 2) and at the days indicated. Plasma samples were denatured within 75 seconds from collection. Plasma samples were electrophoresed, blotted, and incubated with labeled mAb H206. Autoradiographs from blots are shown (A) and were quantified from the first cycle of treatment of 4 patients (B). (A) The major band in pretreatment plasma—α′C3b₂-HC, representing the reduced form of C3b₂-IgG—is marked. The unlabeled dashed arrow points to the high–molecular-weight C3b-containing complexes appearing after infusion of IVIG. (B) Total C3b-containing complexes comprised label in all complexes above α′C3 to the beginning of the stacking gel. Data are expressed in percent of the pretreatment values (mean ± 1 SD).