Anti-non-Gal IgM and IgG serum antibodies were evaluated using GalT-KO PBMCs and mTg Tri-KO PBMCs5 (link),19 (link) (Table S1). Serum Ab binding to cells was detected by FCM (FACS CANTO II, BD Biosciences). FITC-conjugated goat anti-human IgM or IgG antibody (Invitrogen) were used as described.19 (link) Data were expressed as median fluorescence intensity (MFI) “antibody index (Ab index)” which was calculated as follows: (Experimental median fluorescence intensity (MFI) – Negative control MFI)/(Positive control MFI – Negative Control MFI) × 100. Positive control was the recipient serum against Gal + pig PBMC, and negative control was secondary ab (IgM or IgG) with target cells without serum.