β2 integrin is necessary for lytic granule convergence to the MTOC in human ex vivo NK cells. All human samples were obtained after informed donor consent in accordance with the Declaration of Helsinki and were used with approval of the Institutional Internal Review Board for the Protection of Human Subjects of the Children’s Hospital of Philadelphia and/or National Institutes of Allergy and Infectious Diseases. (A) Confocal microscopy of fixed cells showing representative eNK cells from (top) a healthy donor and (bottom) a LAD-1 patient conjugated to susceptible K562 cells. After 30 minutes at 37°C on poly-L-lysine–coated glass slides (PolyPrep; Sigma-Aldrich), conjugates were fixed and stained with anti–α-tubulin (green), anti-perforin (red), and Phalloidin-F-actin (blue). TL, transmitted light. (B) Lytic granule distance from the MTOC in 15 cells; error bars show ±SD. Mean distance of lytic granules from the MTOC in LAD-1 eNK cells was significantly different from that in control eNK cells (*P < .05). (C) Standard 4-hour Cr51 cytotoxicity assay showing impaired NK cell lytic function by LAD-1 patient peripheral blood mononuclear cells (red) compared with healthy control (black). (D) Reduced CD11a expression on LAD-1 (dashed histogram) CD56⁺CD3⁻ eNK cells as detected by flow cytometry compared with healthy donor control (solid histogram). (E) Conjugate formation between control (black) and LAD-1 (white) eNK cells as determined by fluorescence-activated cell sorter–based conjugation assays. Control values for each time point were normalized to 1.