Profiling natural serum antibodies of non‐human primates with a carbohydrate antigen microarray

Background Engineering of α‐Galactosyltransferase gene‐knockout pigs circumvented hyperacute rejection of pig organs after xenotransplantation in non‐human primates. Overcoming this hurdle revealed the importance of non‐α‐Gal carbohydrate antigens in the immunobiology of acute humoral xenograft rejection. Methods This study analyzed serum from seven naïve cynomolgus monkeys (blood type O/B/AB = 3/2/2) for the intensity of natural IgM and IgG signals using carbohydrate antigen microarray, which included historically reported α‐Gal and non‐α‐Gal carbohydrate antigens with various modifications. Results The median (range) of IgM and IgG signals were 12.71 (7.23‐16.38) and 9.05 (7.23‐15.90), respectively. The highest IgM and IgG signals with narrowest distribution were from mono‐ and disaccharides, followed by modified structures. Natural anti‐α‐Gal antibody signals were medium to high in IgM (11.2‐15.9) and medium in IgG (8.5‐11.6) spectra, and was highest with Lac core structure (Galα1‐3Galβ1‐4Glc, iGb3) and lowest with LacNAc core structure (Galα1‐3Galβ1‐4GlcNAc). Similar signal intensities (up to 15.8 in IgM and up to 11.8 in IgG) were observed for historically detected natural non‐α‐Gal antigens, which included Tn antigen, T antigen, GM2 glycolipid, and Sda antigen. The hierarchical clustering analysis revealed the presence of clusters of anti‐A antibodies and was capable of distinguishing between the blood group B and AB non‐human primates. Conclusions The results presented here provide the most comprehensive evaluation of natural antibodies present in cynomolgus monkeys.