Natural anti-αGal Ab levels and the influence of 3-Gy irradiation. (A) ELISA assay demonstrating that IgM and IgG natural anti-αGal Ab levels in naive GalT^–/– mice increase with age. Serum was isolated from naive GalT^–/– mice and anti-αGal Ab levels were assessed by ELISA (n = 81). OD indicates optical density. (B) Three-gray irradiation decreases B-cell numbers in GalT^–/– mice (n = 5 in each group). The percentage of CD4⁺, CD8⁺, and B lymphocytes in PBCs was assessed by flow cytometry. CD4⁺ cells (□), CD8⁺ cells (▪), CD19⁺ cells (○). (C) Influence of 3-Gy irradiation on anti-αGal Ab levels were assessed by ELISA. IgM anti-αGal Abs rise at 3 weeks after irradiation in the absence of GalT BMT. Irradiated mice (□), nonirradiated control mice (•;n = 7, respectively). Error bars indicate SE.