Effects of leukocyte serprocidins on the cleavage of CD11b and the detachment of adherent PMNs from immobilized FBG. (A) The detachment of adherent PMNs. The fMLP (10−7M)–induced PMN adhesion to immobilized FBG was performed in the presence of NE inhibitor (10μM), anti-NE mAb NP57 (50 μg/mL) or serine protease inhibitor ABESF (50μM). (B) The cleavage of CD11b by NE or other serprocidins. All PMNs (adherent or detached) were collected and blotted with antibody R7928A. Data represent 3 or more independent experiments. (C) “Initial” detachment of individual adherent PMNs measured using the Zigmond chamber assay (n = 8). (Inset) Phase contrast images of migrating PMNs in the presence (top) or absence (bottom) of AEBSF. Note that in the presence of AEBSF, PMN has a typical extended “tail” (arrowhead).