Dahl-2bF8^tgBMT rats are tolerized to platelet-targeted FVIII expression. Blood samples were collected from Dahl-FVIII^−/− recipients via ventral tail artery blood draw at various time points after BMT from 2bF8^tg rats. Plasmas were isolated, and inhibitor titers were determined by using a chromogenic-based Bethesda assay. Dahl-FVIII^−/− rats that did not receive BMT but received various numbers of rhFVIII infusions were used as controls for inhibitor development studies. (A) Anti-FVIII inhibitor titers. (B) Incidence of anti-FVIII inhibitor development. None of the 2bF8^tg-BMT recipients developed anti-FVIII inhibitors.