C3a modulates SDF-1–dependent adhesion of CD34⁺ cells to VCAM-1.

Cells resuspended in the adhesion medium with or without C3a (1 μg/mL) were added to the wells and allowed to settle and were subsequently stimulated with 1 μM of recombinant human SDF-1β for 2 minutes. In blocking studies cells were incubated with 10 mg/mL anti–VLA-4 integrin mAb (clone P1H4, Chemicon) for 30 minutes prior to the adhesion assay. Data are pooled from quadruplicate samples from 4 independent experiments. *P < .01.