Protease-independent migration of other leukocytes. (A) Release of FITC from FITC-containing 3D collagen matrix by migrating SupT1 lymphoma cells, CD8+ T blasts, U937 monocytic cells, and monocyte-derived human dendritic cells. Cells were cultured in FITC-collagen for 40 hours in the absence or presence of protease inhibitor cocktail. Data represent the means ± SD from 3 independent experiments. High nonspecific fluorescence of unclear origin was obtained for supernatants from dendritic cells only. This fluorescence was neither sensitive to protease inhibitors nor did it reflect fiber degradation, as previously shown by confocal analysis.46 (B) Mean velocity and percentage of locomoting cells in the absence or presence of inhibitor cocktail. Data show the mean activities over time (>1 hour) and standard deviations from 3 independent experiments (120 cells) obtained from cell tracking. (C) Amoeboid movement of U937 cell resulting in the formation of a constriction ring (arrow) that remains unchanged in position. Bar, 10 μm.
