Defective CXCR4 internalization and desensitization in WHIM^wt lymphocytes. (A-B) CXCL12- and PMA-promoted CXCR4 internalization in CD4⁺-gated T cells from WHIM^wt patients P3 (A) and P4 (B) and healthy subjects (□, and patient P4's mother ▦ and father ▨). (B) CCL21-promoted CCR7 endocytosis in CD4⁺-gated T cells from the patient P4 and healthy subjects is shown. Values, expressed as percentage of unstimulated cells, are from 3 independent experiments (mean ± SEM). ^*P < .05 compared with healthy subjects. (C-D) CXCL12-triggered actin polymerization in CD4⁺-gated T lymphocytes from WHIM patients P3 (C, left panel) and P4 (D) and healthy individuals (□ and patient P4's mother ▵ and father ○). Panel C (right) shows kinetics of actin polymerization following CCL21 stimulation. Arrows indicate chemokine stimulation. The results displayed are from 1 representative experiment of 2.