Cleavage of FRETS-VWF73 by membrane-bound proteases on neutrophils. (A) The (commercial) FRETS-VWF-73–cleaving activity of 2.5% normal pooled plasma (NPP) or 2.5% ADAMTS13-deficient TTP plasma in the presence of resting or PMA-activated neutrophils (105 cells/mL). Resting or activated cells were resuspended in 2.5% plasma mixed in reaction buffer. Activities are represented relative to 2.5% NPP alone, which is designated as 100% activity. (B) The cleaving activity of 2.5% wild-type (WT) or 2.5% ADAMTS13-deficient (ADAMTS13−/−) mouse plasma in the presence of resting or PMA-activated neutrophils (105 cells/mL). Activities are represented relative to WT mouse plasma, which is designated as 100% activity. Results shown in panels A and B are mean values (± SD) from 2 combined representative experiments (N = 4). ▨ represents activated neutrophils. The P values were determined by Student t tests.
