Selection of NK cell clones bearing activating and/or inhibiting receptors for HLA-I antigens.

NK cell clones, selected for the homogeneous expression of CD158a, CD158b, p50.3, and CD94, were analyzed in a 4-hour killing assay using the FcγR⁺ P815 target cells in the presence of mAb recognizing the indicated surface molecules. An HLA-I receptor was defined as inhibiting or activating when P815 killing at the E/T ratio of 20:1 or 2:1 was either inhibited or increased, respectively, as described.1-3 10-13 Surface phenotype of each clone and functional behavior of HLA-I receptor are indicated above each panel. nil indicates lysis of P815 cells in the absence of any mAb. Results obtained with anti-CD56 mAb, as isotype-matched negative control antibody, are shown in each panel. In some experiments, results obtained with an anti-CD16 mAb, used for comparison as antibody to an NK-triggering molecule, are shown. Results are expressed as⁵¹Cr-specific release, and E/T ratios used are indicated in each panel.