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Human antibody reactivity against xenogeneic N ‐glycolylneuraminic acid and galactose‐α‐1,3‐galactose antigen
Author(s) -
Hurh Sunghoon,
Kang Bohae,
Choi Inho,
Cho Bumrae,
Lee Eun Mi,
Kim Hwajung,
Kim Young June,
Chung Yun Shin,
Jeong Jong Cheol,
Hwang JongIk,
Kim Jae Young,
Lee Byeong Chun,
Surh Charles D.,
Yang Jaeseok,
Ahn Curie
Publication year - 2016
Publication title -
xenotransplantation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.052
H-Index - 61
eISSN - 1399-3089
pISSN - 0908-665X
DOI - 10.1111/xen.12239
Subject(s) - hek 293 cells , antibody , antigen , complement system , xenotransplantation , chemistry , immunology , microbiology and biotechnology , transplantation , medicine , biology , receptor , biochemistry
Abstract Background Despite the development of α1,3‐galactosyl transferase‐knockout ( GTKO ) pigs, acute humoral xenograft rejection caused by antibodies against non‐Gal antigens, along with complement activation, are hurdles that need to be overcome. Among non‐Gal antigens, N ‐glycolylneuraminic acid (Neu5Gc) is considered to play an important role in xenograft rejection in human. Methods We generated human embryonic kidney 293 ( HEK 293) cells that expressed xenogeneic Neu5Gc ( HEK 293‐ pCMAH ) or α1,3Gal ( HEK 293‐ pGT ) antigen and investigated the degree of human antibody binding and complement‐dependent cytotoxicity ( CDC ) against these antigens using 100 individual human sera. Results Both IgM and IgG bound to α1,3Gal, while only IgG bound to Neu5Gc. Of the ABO blood groups, the degree of IgG binding to α1,3Gal was highest for blood group A. The degree of CDC against HEK 293‐ pCMAH cells was significantly lower than that against HEK 293‐ pGT cells. However, CDC against HEK 293‐ pCMAH cells was significantly higher than that against control HEK 293 cells. In addition, the severity of CDC against HEK 293‐ pCMAH cells positively correlated with that against GTKO pig aortic endothelial cells ( PAEC s), suggesting that Neu5Gc is the main antigen in GTKO PAEC s. Similar to antibody‐binding activity, only IgG binding correlated with CDC against HEK 293‐ pCMAH cells. The most common subclass of IgGs against Neu5Gc was IgG1, which typically induces strong complement activation. Conclusions We showed that IgG‐mediated CDC was detected in Neu5Gc‐overexpressed HEK 293 cells incubated with human sera; however, this antibody reactivity to Neu5Gc was highly variable among individuals. Our results suggest that additional modifications to the CMAH gene should be considered for widespread use of pig organs for human transplants.