Human neutrophils release proteases cleaving rhuVCAM-1.

(A) FDCP1–huVCAM-1 cells were incubated for 1 hour at 37°C in the presence of an equivalent volume of nonconditioned medium (black), NHB-conditioned media (orange), human BM stromal cell–conditioned media (BMS; blue), human BM CD34⁻ cell–conditioned media (purple), or human PB neutrophil–conditioned media (Neut; red) and were stained with the mAb 6G10. The gray histogram is the staining with an isotypic control. Media conditioned by cells from 6 healthy donors gave similar results. (B) Western blot analysis of rhuVCAM-1 incubated for 15 minutes at 37°C in the presence of medium conditioned either by human BM stroma (lane b), NHB (lane c), human BM CD34⁻ cells (lane d), or human PB neutrophils (lane e), or of purified human NE (lane g), CG (lane h), P3 (lane i), MMP-9 (lane j), and granzymes B (lane l), H (lane m), or M (lane n). Undigested rhuVCAM-1 is shown in lanes a, f, and k.