Anti-PECAM/beads bind to PECAM-expressing cells.

(A-D) The 150-nm fluorescent beads coated with control IgG (A,B) or anti-PECAM (C,D) were incubated with REN/PECAM cells (A,C), or HUVECs (B,D) for 1 hour at 37°C, then washed, fixed, and imaged by fluorescence microscopy. Note the specific association of anti-PECAM/beads to PECAM-expressing cells (C,D). Bar, 10 μm. (E-H) Anti-PECAM/beads (light bars) or IgG/beads (dark bars) with effective diameters of 130 nm (E), 150 nm (F), 310 nm (G), or 560 nm (H) were incubated with REN cells, REN/PECAM cells, or HUVECs for 1 hour at 37°C. The cells were then washed, fixed, and analyzed by fluorescence microscopy. PECAM-expressing cell lines showed significantly more binding of anti-PECAM/beads than of IgG/beads (P < .001). There was little, if any, bead binding to nontransfected REN cells.