AP-specific components FB, FD and FP attach to ULVWF strings secreted by, and anchored to, stimulated HUVECs.

<p>HUVECs were stimulated with 100 µM histamine and stained with rabbit anti-VWF plus secondary fluorescent anti-rabbit IgG-488 (green). Cells were then p-formaldehyde-fixed and stained with goat IgG antibody to human FB (A), antibody to human FD (B), and antibody to human FP (C) plus secondary fluorescent anti-goat IgG-594 (red). The HUVEC nuclei were labeled with DAPI (blue). In (A) are: (1) ULVWF (488-nm, green); (2) FB (594-nm, red); and (3) ULVWF and FB combined image; (4) Graph of fluorescent intensities (y-axis) measured from identical locations in ULVWF string images (488-nm, green) and in complement component proteins images (594-nm, red) are plotted against the ULVWF string length (in microns, x-axis). The black line indicates the background intensities measured in the 594-nm images. (5) ULVWF intensities were measured along lines of ULVWF strings detected at 488-nm (shown by dotted line); (6) FB intensities were measured in 594-nm images along lines at identical locations (shown by lower dotted line) as determined in (5). Background intensities were also measured in 594-nm (red) images at parallel locations (shown by upper dotted line) away from the area of interest. Similar types of images are shown using antibody to human FD in (B) panels 1–6 and antibody to human FP in (C) panels 1–6 to identify the complement component attached to the HUVEC-secreted/anchored ULVWF strings. In (C) panel 6, only the locations of the background intensities are identified by the dotted line. The white arrows in (3) indicate FB (A), FD (B) and FP (C) attachment to the strings. Images were selected from 5 (FB and FD) and 4 (FP) independent experiments.