Impaired CXCR4 signaling in WHIM PMNs. (A,C) CXCL12-triggered actin polymerization in overnight-cultured PMNs from WHIM^wt patient P4 (A, •) or WHIM¹⁰¹³ patient P2 (C, •) compared with those from healthy donors (□ and patient P4's mother [▵] and father [○]). Results are from 1 representative experiment of 3. (B,D) CXCL12-induced chemotaxis of PMNs from patients P4 (B, ▪) and P2 (D, ▪) were compared with those of cells from healthy donors (□, and patient P4's mother [▦] and father [▨]). Inhibition of CXCL12-induced chemotaxis by addition of AMD3100 in both chambers is shown in panel B. Results (mean ± SEM) are from 3 independent experiments and are expressed as percentage of input PMNs that migrated to the lower chamber. ^**P < .005 compared with PMNs from healthy subjects.