Figure 3.
CD81 cross-linking has opposite effects on NK and T cells. NK (A) and T (B) cell clones from the same healthy donor were stimulated for 24 h and the supernatants were analyzed for the presence of IFN-γ. The NK cell clones (A) were stimulated with the indicated concentrations of anti-CD16 alone (•) or in combination with 10 μg/ml of: anti-CD81 (○) or anti-HCV-E2 + rHCV-E2 (□). The “classical” TCR αβ+ T cell clones (B) were stimulated with decreasing concentrations of anti-CD3 alone (•) or in the presence of 10 μg/ml: anti-CD81 (○) or anti–HCV-E2 + rHCV-E2 (□). Control antibodies for anti-CD56 (NK cells) or anti-class I (T cells) had no effect and neither did treatment with the anti-HCV-E2 reagent alone (data not shown). In (C) the effects of CD81 ligation on different T and NK cell subsets is summarized. NKT (gray bar), KIR+ T (stippled bar), CD16+ T (hatched bar), Th1 (striped bar), Th2 (white bar, and NK cell (black bar) clones were obtained from the same healthy donor by single cell sorting. The scheme represents the effect of CD81 cross-linking on these different cell types when activated by the appropriate stimulus (anti-CD16 mAb for NK cells, anti-CD3 mAb for the other T cell types). Cytokine production (IFN-γ: KIR+ T; Th1; CD16+ T, NK or IL-4: Th2 cell clones), or proliferation (NKT) were used as readouts for CD81-mediated costimulation or inhibition. Results are presented as percentage change compared with treatment with 0.3 μg/ml of anti-CD16 (NK cells) or anti-CD3 (T cells). CD16+ T cells were also analyzed for proliferation, their ability to produce TNF-α and their expression of activation markers after CD81 ligation. In all cases this treatment had no effect (data not shown).