Restimulation of FVIII-specific memory B cells in vitro. Spleen cells were obtained from hemophilic mice treated with 4 intravenous doses of 200 ng (80 U/kg) FVIII and depleted of CD138⁺ ASCs. The remaining CD138^– cell population was restimulated with 10 ng/mL FVIII and analyzed for newly formed ASCs after 1, 3, and 6 days of culture. ASCs were analyzed by ELISPOT assays as described.¹⁹