Down-regulation of ChemR23 in activated NK cells. Purified peripheral blood NK cells were cultured in the absence or presence of 100 U/mL IL-2 for various time and then assessed by 2-color immunofluorescence and flow cytometry for the expression of ChemR23 (upper panel A) or CXCR1 (lower panel A) in combination with CD56. This experiment is representative of 4 independent donors. (B) Real-time polymerase chain reaction (PCR) evaluation of ChemR23 expression in NK cells cultured with IL-2 or IL-15 (20 ng/mL) for 24 hours. One experiment representative of 3 is shown. (C) NK cells were cultured with medium (control) or with IL-2 for 4 days and then tested for their ability to migrate in response to chemerin. Results are the average values of 2 experiments.