Integrin functions on RIAM^−/− PMNs are severely impaired. (A) Representative FACS blots showing surface levels of αL integrin, αM integrin, β2 integrin, CD44, CD43, and PSGL-1 on wt (green), RIAM^−/− (red), and talin-1^−/− (blue) PMNs. BM cells were gated for high Gr1 expression. Isotype control staining is shown in light gray. (B) Static adhesion of untreated (resting), TNF-α–, and PMA-treated BM-derived PMNs from wt, RIAM^−/−, and talin-1^−/− mice on ICAM-1, fibrinogen, or VCAM-1 (n = 5 independent experiments). (C) Number of adherent (not spread) and spread wt and RIAM^−/− PMNs seeded on immune complexes for 30 minutes were individually counted (n = 3 independent experiments). (D) Relative amount of fluorescently labeled Escherichia coli particles phagocytosed by wt, RIAM^−/−, talin-1^−/−, and β2 integrin^−/− at 4°C and 37°C (n = 8, 8, 8, 3). (E-F) Oxidative burst measured in wt, RIAM^−/−, and talin-1^−/− PMNs after stimulation with TNF-α (E) and PMA (F), respectively. P values for TNF-α stimulation: wt vs RIAM^−/− at 50 minutes (P < .005) and at 60 minutes (P < .001); wt vs talin-1^−/− at 40 minutes (P < .005) and at 50 minutes and 60 minutes (P < .001), RIAM^−/− vs talin-1^−/− at 40 minutes and 50 minutes (P < .01) and at 60 minutes (P < .005). P values for PMA stimulation: wt vs talin-1^−/− at 40/50/60 minutes (P < .05; n = 5). Data are shown as mean ± SD; P values indicate significant differences and were calculated with the Student t test. ctl, control; fov, field of view; n.s., not significant; Rel., relative; rest., resting.