Exacerbated CXCL12-induced chemotaxis of WHIM leukocytes. (A) CXCL12-, CCL21-, CCL4-, or CCL5-induced migration of PBMCs from patients P3 (left panel, ▪) and P4 (right panel, ▪) and healthy donors (□, and patient P4's mother [▦] and father [▨]). Transmigrated cells recovered in the lower chamber were counted by flow cytometry with gating on forward and side scatter to exclude debris and monocytes. (B) CXCL12-promoted chemotaxis of PBMCs from WHIM¹⁰¹³ patients P1 (left panel, ▦) and P2 (right panel, ▪) or healthy individuals (□). Inhibition of cell migration by AMD3100 added in both chambers and chemotaxis in response to CCL4 are shown. (C) Dose-dependent CXCL12-induced chemotaxis of A0.01 T cells transduced with the indicated CXCR4 variants (□, CXCR4^wt; ▦, CXCR4¹⁰⁰⁰; ▪, CXCR4¹⁰¹³). Parental A0.01 T-cell line was consistently unresponsive to CXCL12. (A-C) Results (mean ± SEM) are from 3 independent experiments and are expressed as percentage of input cells that migrated to the lower chamber. ^*P < .05 and ^**P < .005 compared with leukocytes from healthy subjects or with CXCR4^wt-expressing A0.01 T cells.