Antigen-specific ASC after experimental vaccination. Frequencies of total IgG and TT and DT–specific antibody–producing cells were enumerated by ELISPOT on day 0 and day +7 after vaccination. The responses of 10 healthy donors (HD), 5 patients receiving low doses of B cells (DL1/2), and 9 patients receiving a high-dose (DL3/4) of B cells are depicted. The frequency was calculated as the percentage of B cells seeded in ELISPOT wells. ns, not significant; ∗∗P < .01; ∗∗∗∗P < .0001. Dotted lines indicate the lower detection limits.