P-gp expression on NK cells. (a through c) are NK cells from normal donors, (d through l) are those from patients, and (m) and (n) are NK cell lines. (d through l) correspond to patients 1 through 9 of Table 1, respectively. (m) is the cell line NK92, and (n) is the cell line NKL. Dark zone shows the results with MRK16 MoAb, and clear zone shows the results with control IgG2a MoAb. In normal NK cells (a through c), P-gp was measured in two subsets, CD16⁺CD56⁺ (dark zone) and CD16⁻CD56⁺ (gray zone).