Tolerance induction in GalT BMT mice. (A) Anti-αGal Ab levels were assessed by ELISA at 15 weeks after BMT in mice that received transplants of WT hearts. REV BMT mice received transplants of WT hearts at 4 weeks after BMT and were killed when they rejected the graft; therefore, this data ends at 5 weeks. GalT-transduced BMT mice (□), REV (•) (n = 5 each). (B) Levels of IgG subtypes in the sera were analyzed by ELISA before BMT, 9 weeks after BMT in GalT-transduced BMT mice, and 5 weeks after BMT in REV BMT mice (n = 5 each). □ indicates IgG1; ▦, IgG2a; ▧, IgG2b; and ▪, IgG3. IMM indicates immunized control mice (n = 5 each); HTx indicates heart transplantation. (C) To assess the existence of anti-αGal Ab–producing cells, spleen, BM, and PerCs were collected and assessed using an ELISPOT assay. Anti-αGal Ab–producing B cells are not detected in GalT BMT chimeras. GalT-transduced BMT mice (□), REV (•), WT (▪), immunized GalT^–/– mice (○) (n = 5 each). Data are shown as mean ± SE.