Transient immune suppression does not prevent the anti-FVIII immune response. Hemophilia dog #1 was 17 months old and weighed 10.6 kg when the procedure was performed. A total of 2 × 109 autologous BOECs that expressed 1.0 U FVIII per 106 cells over 24 hours in vitro were implanted into 18 sites (1.1 × 108 cells per site). To prevent bleeding problems, the dog received 3 infusions of canine cryoprecipitate (black arrows) before and after the procedure. This dog received 6 once-per-week infusions of cyclophosphamide (200 to 250 mg/m2) (gray arrows), the first of which occurred on the day before the cells were implanted. Plasma samples were collected at each of the indicated time points. (A) FVIII activity (FVIII:C) and FVIII antigen (FVIII:Ag) levels were measured, and the results were compared against pooled normal canine plasma samples isolated from 8 healthy dogs. The FVIII:C and FVIII:Ag values presented in the figure are relative to the canine pooled plasma sample that was arbitrarily set at 100%. (B) Anti-FVIII inhibitory antibodies were detected by using a standard Bethesda assay. Anti-cFVIII IgG1 and IgG2 antibodies were detected by a cFVIII-specific ELISA.
