Kinetics of NKG2D ligands expression on SEB-activated CD4 ⁺ and CD8 ⁺ T cells in several healthy donors. Expression levels of NKG2D ligands were analyzed on SEB-activated CD4⁺or CD8⁺ T lymphocytes from different healthy donors, as described in the legend of Figure 1. Each donor is represented by ○. The dashed line delimits negative donors (MFI values < 2). Mean values of MFI are indicated by horizontal bars and were calculated on positive donors (MFI values > 2). Thirteen donors were examined at days 3, 5, and 7, and 6 donors were examined at days 3 and 5.