TACI is required for differentiation of B cells into ASCs. TACI-ko animals had decreased NP-specific IgM ASCs or NP-specific IgG ASCs compared with wild-type. ASCs were enumerated in B cells isolated from the spleen (A-B) or in bone marrow cell suspensions (C-D) of C57BL/6-wt or C57BL/6-TACI-ko 21 days after immunization, by ELISPOT. Below the graphs, the diagrams show the ELISPOT wells from which the ASCs were enumerated and plated with 10⁶, 5 × 10⁵, or 10⁵ cells, as indicated. Values were compared by t test. Significant differences: *P < .05; **P < .01. Data resulted from the analyses of 5 wild-type mice and 4 TACI-ko mice.