Effect of BAR CD8 T cells on the antibody response to FVIII in vivo. (A) Schematic diagram of immunization and sample collection with n = 5 per group of A2/C2-BAR– or OVA-BAR–injected animals. (B) Anti-FVIII concentrations in serum at different time points after injecting BAR T cells and FVIII immunization. P < .05 at weeks 4, 5, 9, and 10; P < .01 at week 12. (C) FVIII-specific IgG spot formation by naïve B cells isolated from mouse injected with A2/C2-BAR or phosphate-buffered saline upon coculture with FVIII (1 μg/mL) for 5 days (P = .0087). Bars indicate standard error. IFA, incomplete Freund’s adjuvant; rFVIII, recombinant FVIII; s.c., subcutaneously.