Impaired LAD-III NK cell cytotoxicity on triggering of a single receptor. (A) P815 cells were incubated either with no mAb or with various mAbs (indicated on the x-axis of the figure) to stimulate redirected NK cell cytotoxicity. The E:T ratio was 3:1. Gray columns represent the healthy NK cell cytotoxicity; and white columns, the cytotoxicity of the LAD-III NK cells. Data are mean ± SD. Error bars (SD) are derived from triplicates. **P < .005 (2-tailed t test). Shown is 1 representative experiment of 5 performed. (B) FACS analysis of JEG3 cells transfected to express various NKG2D ligands (left panels). The same cells were also stained for the expression of ICAM-1 (right panels). The gray empty histogram represents the staining of the cells with a control mAb; and the black empty histogram, the specific staining. Figure shows 1 representative experiment of 3 performed. (C) The JEG3 parental cells and the various transfectants were tested for killing by bulk NK cell cultures derived from a healthy control (gray columns) or by NK cells derived from the LAD-III patient (white columns). The E:T ratio was 5:1. Figure shows 1 representative experiment of 2 performed. Data are mean ± SD. Error bars (SD) are derived from triplicates. *P < .05 (2-tailed t test). **P < .005 (2-tailed t test). NS indicates not significant. (D) NK cells derived from a healthy donor or from the LAD-III patient were assayed for their ability to kill the B-cell line Daudi or Daudi coated with anti-CD20 (1 μg/mL). Data are mean ± SD. Error bars were derived from triplicates. Shown is 1 experiment of 3 performed.