Influence of milatuzumab on the migration characteristics of CD19+ B cells and subsets in vitro. (A) Spontaneous baseline migration of B cells in a transwell migration assay. Peripheral blood mononuclear cells were incubated for 90 minutes at 37°C in 5% CO2 with or without milatuzumab (n = 8) or IgG1/IVIG (n = 6) and allowed to migrate without any chemokine added. Percentages of migrated cells are shown. Migration was significantly enhanced (Wilcoxon test) by milatuzumab in CD19+ B cells, especially in CD27- naïve B cells. (B) Effective CXCL12-dependent net migration determined for each individual by subtraction of the baseline migration - see (A) - from the total migration toward CXCL12 (not shown). A significant enhancement of the migration of CD19+ B cells, especially of CD27- B cells by milatuzumab, was identified (Wilcoxon test). In control experiments, IgG1/IVIG had no influence on migration. *P ≤ 0.05; **P ≤ 0.01. CXCL, CXC motif ligand; IVIG, intravenous immunoglobulin; ns, not significant.