Expression of Gal and Neu5Gc on erythrocytes by flow cytometry. Erythrocytes from Dom, GGTA1 KO and GGTA1/CMAH KO pigs, baboons, chimpanzees, and humans were labeled with fluorescently conjugated Sambucus nigra (SNA) lectin (red line) to detect Neu5Ac linked α 1,6 galactose expression (top panel) were used as a positive control for the presence of erythrocytes. Fluorescently conjugated IB4-lectin was used to assess Gal expression (middle panel)(red line), and anti-Neu5Gc antibody was used to examine the expression of Neu5Gc epitopes (bottom panel)(red line). Unstained erythrocytes are shown as negative controls (black line) for SNA and IB4-lectins, and an isotype control for Neu5Gc. Histograms are representative of 3 individual experiments.