Rhophylac

The IgG preparations used in this study included Sandoglobulin, Privigen, Hizentra, Cytogam and Rhophylac (CSL Behring AG), Gamunex (Talecris Biotherapeutics) and Intratect (Biotest). Sandoglobulin and Privigen (IgG content ≥98%) contained ≤2% and ≤0.01% IgA, respectively, and only traces of IgM, IgD, and IgE (as reported by CSL Behring). The IgG subclass composition of Sandoglobulin was analyzed by nephelometry (Quest Diagnostics) and contained principally IgG₁ (61%) and IgG₂ (32%), with small quantities of IgG₃ (5%) and IgG₄ (2%). Privigen contained 66% IgG₁, 29% IgG₂, 3% IgG₃, and 3% IgG₄ (as reported by CSL Behring). To remove the stabilizing sucrose component of Sandoglobulin, dialysis was performed as previously described (62 (link)). Further information on the immunoglobulin preparations is provided in table S2.
A control IgG preparation (IgG control mix) was made by mixing 2 monoclonal human myeloma proteins, IgG₁λ (67%) and IgG₂κ (33%), purchased from Sigma-Aldrich. This process resulted in a κ/λ ratio of 0.5, which is well within the range found in normal serum (0.26–1.65). Anti-human IgG monoclonal antibody (clone HP-6043-Biot), recognizing all IgG subtypes, and Streptavidin-Alexa633 were purchased from Invitrogen (Invitrogen, Life Technologies).