FIG. 6.

Cytotoxicity by NK cells can be blocked with UL18-Ig proteins. The percent specific lysis of BHK-CD64 cells by YT-ILT2 cells at an effector-to-target cell ratio of 50:1 in the presence of different amounts of UL18-Ig soluble proteins is depicted. Target cells were preincubated with the indicated amounts of either antibody or UL18-Ig constructs. After 30 min, effector cells were added and a 4-h ⁵¹Cr release assay was performed. These data are representative of those from three independent experiments with YT-ILT2 cells.