Figure 6. Blocking E⁻H⁺ integrin binding to neutrophil ICAM-1 promotes its transition to E⁺H⁺.

(a) Schematic showing the hypothesis that the cis interactions of E⁻H⁺ integrin (both LFA-1 and Mac-1) and neutrophil ICAM-1 may stabilize the E⁻H⁺ integrin. (b) Integrin clusters (E⁺H⁻ red, E⁻H⁺ green, E⁺H⁺ yellow) on arresting neutrophils rolling on P-selectin/ICAM-1/IL-8 with or without neutrophil ICAM-1 blocking by mAbs HA58 and R6.5; scale bar, 5 μm. (c–e) ICAM-1 blocking decreased the number of E⁻H⁺ clusters at arrest (c, n=15 cells). The number of E⁺H⁺ (d, n=15 cells) and E⁺H⁻ clusters (e, n=15 cells) at arrest with or without ICAM-1 blocking. (f) Dynamics of E⁻H⁺ clusters with or without ICAM-1 blockade on cells rolling on P-selectin/ICAM-1/IL-8. (g,h) ICAM-1 blocking decreased the duration of E⁻H⁺ clusters before transitioning to E⁺H⁺ clusters (g, n=16 clusters). Duration histograms (h, bin=1 s). Mean values and s.e.ms (error bars) were presented in (c–e) and (g). Log Gaussian (ICAM-1 blk) and Lorentzian (isotype) fits were used in h. n.s. P>0.05, ** P<0.01, *** P<0.001, **** P<0.0001 in unpaired student t-test. n.s., not significant.