Receptor engagement, stimulation of cell proliferation, and chemotaxis by SDF-1 species. (A) Calcium fluxes in fura-2–loaded Jurkat cells in response to varying concentrations of recombinant SDF-1α (1-68) and SDF-1β (1-72) and synthetic SDF-1α (1-67) and SDF-1α 3-67. The results reflect fluorescence measurements as a ratio of excitation at 340 and 380 nm. Arrows indicate chemokine addition. (B) DW34 pre–B-cell proliferation in response to varying concentrations (1.9 to 240 ng/mL) of recombinant full-length SDF-1β (1-72), SDF-1α (1-68), SDF-1α 1-67 (generated by 10 minutes of incubation with 10% fresh human serum at room temperature), and SDF-1α 3-67 (generated by 20 hours of incubation with fresh serum). The results reflect the mean counts per minute (cpm) per culture (± SEM) of triplicate determinations; a representative experiment of 5 performed is shown. (C) DW34 pre–B-cell proliferation in response to varying concentrations (12.5 to 100 ng/mL) of recombinant full-length SDF-1α (1-68), synthetic SDF-1α 1-67, and synthetic SDF-1α 3-67. The results reflect the mean counts per minute per culture (± SEM) of triplicate determinations; a representative experiment is shown. (D) BL-41 B-cell chemotaxic response to recombinant full-length SDF-1α (1-68) and synthetic SDF-1α (1-67) at varying concentrations (5 to 625 ng/mL). The results reflect the mean (± SEM) number of cells that have migrated to the lower chamber in 5 experiments performed.