Differential Immune Responses to Alpha-gal Epitopes on Xenografts and Allografts: Implications for Accommodation in Xenotransplantation
Overview
Authors
Affiliations
Xenograft recipients produce large amounts of high-affinity anti-Gal IgG in response to Galalpha1-3Galbeta1- 4GlcNAc-R (alpha-gal) epitopes on the graft. In contrast, ABO-mismatched allograft recipients undergo "accommodation," a state of very weak immune response to ABO antigens. These differences in anti-carbohydrate immune response were studied in alpha1,3galactosyltransferase knock-out mice. Pig kidney membranes administered to these mice elicited extensive production of anti-Gal IgG, whereas allogeneic kidney membranes expressing alpha-gal epitopes elicited only a weak anti-Gal IgM response. Anti-Gal IgG response to xenograft membranes depended on helper T cell activation and was inhibited by anti-CD40L antibody. These T cells were activated by xenopeptides and not by alpha-gal epitopes. Moreover, allogeneic cell membranes manipulated to express xenoproteins also induced anti-Gal IgG response. Xenoglycoproteins with alpha-gal epitopes are processed by anti-Gal B cells. Xenopeptides presented by these cells activate a large repertoire of helper T cells required for the differentiation of anti-Gal B cells into cells secreting anti-Gal IgG. Alloglycoproteins with alpha- gal epitopes have very few immunogenic peptides and fail to activate helper T cells. Similarly, ineffective helper T-cell activation prevents a strong immune response to blood group antigens in ABO-mismatched allograft recipients, thus enabling the development of accommodation.
Galili U, Li J, Schaer G Nanomaterials (Basel). 2024; 14(8).
PMID: 38668224 PMC: 11055133. DOI: 10.3390/nano14080730.
Accelerated Burn Healing in a Mouse Experimental Model Using α-Gal Nanoparticles.
Galili U Bioengineering (Basel). 2023; 10(10).
PMID: 37892895 PMC: 10604883. DOI: 10.3390/bioengineering10101165.
Sex, T Cells, and the Microbiome in Natural ABO Antibody Production in Mice.
Adam I, Motyka B, Tao K, Jeyakanthan M, Alegre M, Cowan P Transplantation. 2023; 107(11):2353-2363.
PMID: 37871273 PMC: 10593149. DOI: 10.1097/TP.0000000000004658.
Galili U Front Mol Biosci. 2023; 10:1209974.
PMID: 37449060 PMC: 10338101. DOI: 10.3389/fmolb.2023.1209974.
Ye D, Qu S, Yang Y, Wang Z, Wang Q, Liu W iScience. 2023; 26(5):106647.
PMID: 37168574 PMC: 10165029. DOI: 10.1016/j.isci.2023.106647.