LFA-1 coligation is required for influenza virus to trigger rearrangement of NK cell cortical actin. (A) Top panels: SI images of F-actin in pNK cells stimulated on surfaces coated with influenza virus particles (4000 HU/mL) with or without ICAM-1 (2.5 μg/mL), or the CD2 ligand, CD58 (5.0 μg/mL), with or without ICAM-1. The center of the synapse is enlarged in the panels directly below. Bars represent 1 μm. Bottom middle panels: Holes between actin filaments are represented as heat maps with the smallest holes (0.01 μm2) shown in blue and largest (> 3.0 μm2) shown in red. Bottom panels: The domains within the actin mesh at the NK cell surface interface through which a granule of 200-800 nm in diameter could fit through. Bars represent 5 μm. (B) Surface areas of pNK cells stimulated on coverslips coated with poly-L-lysine (−) and the CD2 ligand CD58, influenza virus particles, or the NKG2D ligand MICA, all with or without ICAM-1. (C) The mean area of holes within the NK cell synapse center for NK cells stimulated as in panel B. (D) The proportion of the NK cell synapse predicted to be penetrable by a granule with a diameter of 250 nm for cells stimulated as indicated. Graphs represent mean ± SEM for n = 30-75 cells across 3 independent experiments. ***P < .0001. **P < .001. *P < .01. NS indicates not significant, analyzed by 1-way ANOVA and compared with poly-L-lysine–coated slides.
