Figure 2.
CD81 engagement blocks the functions of resting NK cells. PBMCs freshly purified from healthy donors were cultured in complete medium on plastic plates coated with no antibody (A and B), 1 μg/ml of CD16 mAb alone (C and D), or 1 μg/ml of CD16 mAb plus 10 μg/ml of CD81 mAb (E and F). After 4 h of Brefeldin-A treatment, cells were stained for intracellular IFN-γ production (A, C, and E) and for the surface expression of the activation marker CD25. The plots in (A–F) represent the CD3-CD56+ subpopulation as defined by the staining in H. In G, CD16 stimulation is specific for NK cells as the CD3+ (T cell) PBMC subpopulation did not produce any IFN-γ, as assayed by intracellular staining.