Inhibition of memory B-cell restimulation by high-dose FVIII in vivo. Titers of anti-FVIII antibodies were measured in hemophilic mice treated with a single intravenous dose of human FVIII (A-B) or murine FVIII (C) as indicated following transfer of CD138^– spleen cells obtained from naive hemophilic mice (B) or hemophilic mice immunized with 4 doses of human FVIII (A) or murine FVIII (C). The error bars represent the standard deviations (n = 7). Spleens from 5 mice were pooled for cell preparation in each experiment. **P < .01 for comparing memory responses with responses in control mice.