Naive B-cell dynamics on 2-dimensional membranes. (A) DIC images of representative nonpolarized and polarized naive B cells on ICAM-1–containing membranes, coated with 100nM CXCL13. Scale bar indicates 2 μm. (B) Frequency of naive B-cell polarization and migration on membranes containing ICAM-1 at different densities and coated with 100nM CXCL13. Filled symbols indicate wild-type B cells; open symbols, CXCR5-deficient B cells. (C) Frequency of naive B-cell polarization and migration on ICAM-1 (150 molecules/μm²)–containing membranes coated with different concentrations of CXCL13. Values for mean velocity and total track length (D) and tracks of migratory B cells (E) on ICAM-1–containing membranes coated with 100nM CXCL13. (F) Representative DIC and IRM images of naive B cells on ICAM-1–containing membranes at specified densities and CXCL13 coating (100nM). Scale bar indicates 5 μm. Data in panels B and C represent the mean ± SEM of 4 experiments; data in panels D and E correspond to the merge of 3 experiments. Gray bar indicates not detected; ns, not significant. ***P < .0001.