Vaccine-specific IgG are produced by both the CD19⁺and the CD19⁻ASC subsets. (A) BD CD19⁺ and CD19⁻ ASC antigen-specific ELISpot results for Daptacel and Fluzone (unpaired Student t test, P < .0327, CD19⁺ mean ± SEM 5.810 ± 1.498, n = 10, CD19⁻ mean ± SEM 15.29 ± 3.814, n = 10). (B) Representative ELISpot wells from 3000 CD19⁺ and CD19⁻ FACS sorted ASCs from BM. (C) 3000 CD19⁺ and CD19⁻ ASCs from spleen were sorted onto Daptacel (n = 4), Fluzone (n = 5), MMR (n = 2), Varicella (n = 2), or IPOL (n = 3) vaccine antigen precoated ELISpot plates and detected for total IgG. (D) Representative ELISpot wells showing sorted ASCs from either CD19⁺ or negative spleen subsets. (E) 10 000 (Flu/Dap) and 30 000 (polio) CD19⁺ ASCs or B cells were FACS sorted from BM, spleen, and tonsil, which indicated antigen-specific CD19⁺ ASCs existed in all tissues. Ag., antigen; Dap., Daptacel; Flu., Fluzone; MMR, measles, mumps, and rubella; Var., Varicella.