Anti–SDF-1 treatment inhibits the stimulatory effect of SDF-1 on colony formation by PB Inc⁺ CD34⁺progenitor cells.

PB Inc⁺ CD34⁺ cells, purified after incubation on a plastic support, were plated in duplicate at a density of 500 cells/mL on semisolid Stem α ID medium containing IL3, IL6, IL11, SCF, G-CSF, GM-CSF, and Epo, in the presence or absence of SDF-1 (0.05 ng/mL) or anti–SDF-1 antibody (5 ng/mL), or isotype control (5 ng/mL). Colonies were scored on day 14. Results are expressed as mean percentages of SDF-1 untreated control cells (CT) ± SD. Control colony numbers were 90.2 ± 8.6 (BFU-E); 12.2 ± 5.4 (CFU-G); 3.5 ± 1.8 (CFU-M); 0.8 ± 0.3 (CFU-GM); and 1.2 ± 1.2 (CFU-Mix). The control plating efficiency (calculated on the total number of colonies) was 19.3% ± 5.4% (n = 3 independent experiments). * indicates significant difference from control values: 0.001 < P < .05.