Rapid formation of IgM-secreting cells is coupled to CXCR4-dependent localization in the bone marrow. (A) Twelve hours following IFA injection total bone marrow or spleen was assayed for IgM secretion by ELISPOT. Data are pooled from 2 experiments. (B) Four hours after IFA + LPS treatment, mice were injected i.p. with 1 mg/kg AMD3100. On day 2, PNA⁺FAS⁺ bone marrow B cells were enumerated by flow cytometry. Data are pooled from 2 experiments. (C) Total bone marrow from mice treated with AMD3100 as in panel B was plated in an IgM ELISPOT. Data are pooled from 3 experiments and significance determined by 1-way ANOVA and Dunnett post test (left panel). The mean spot count for 5 independent experiments is graphed (right panel) comparing IFA-treated mice with IFA + AMD3100. Each point and connecting line represents an individual experiment. (D) Spleens from the experiments shown in panel C, as well as IL-1R^−/− mice were plated in an IgM ELISPOT.