FIGURE 4. Blocking β2 TMD transmission of conformation change in β2 impairs integrin activation during leukocyte adhesion.
(A-C) 3 × 106/ml β2-KO CXCR2-transfected HL-60 cells reconstituted with β2-WT (top panel) or β2-L697P (bottom panel) were labeled with 1μM CellMask Deep Red (blue, membrane) at RT for 10 min, incubated with 5 μg/ml mAb24-AF488 (green, high-affinity β2 integrins) and KIM127-DL550 (red, extended β2 integrins) antibodies for 3 min, and perfused in the flow chamber coated with 2 μg/ml P-selectin, 10 μg/ml ICAM-1, and 5 μg/ml IL-8. Free antibodies remained present during the assay. Typical images of β2-L697P and WT cells 180 s after arrest (A). The total number of clusters (B) and the average cluster area (C) were analyzed. ***P < 0.001 in the 2-tail Student’s t-test. Cells were differentiated with 1.3% DMSO for 5 d prior to the assay. Scale bar 10μm