NK cells degranulating in response to hiPSC lines are enriched for several NK cell receptors.

(A) The degranulation of IL-2-activated NK cells of donor 7 in response to D6-iPSC2 cells is shown. Without contact to hiPSCs only 2.9% of the NK cells expressed the degranulation marker CD107a. After co-culture with target cells for 2 h 25.2% of the CD56⁺ NK cells expressed CD107a at the plasma membrane. 46.7% of the CD107a^- NK cells were KIR positive. Among the CD107a⁺ NK cells 53.0% were KIR positive. The KIR staining was performed with a mixture of all anti-KIR mAbs indicated in Table 1 to cover all KIR molecules. (B) A summary of means and the SEM of CD107a⁺ NK cells of donors 4, 5, and 7 after exposure to three hiPSC lines (D1-iPSC4, D2-iPSC1, D6-iPSC2) and K562 cells is shown (n = 3). (C) In the left panel a summary of means and the SEM of NKG2D⁺, NKG2A⁺, DNAM-1⁺, and KIR⁺ cells among all NK cells exposed to the hiPSCs as well as CD107a^- and CD107a⁺ NK cells is shown. In the right panel a summary of means and the SEM of the MFI of NKG2D, NKG2A, DNAM-1, and KIR on all NK cells exposed to the hiPSCs as well as CD107a^- and CD107a⁺ NK cells is shown. Significant differences between CD107a^- and CD107a⁺ NK cells are indicated (n = 26, *** P<0.001, ** P<0.01, t-test after Bonferroni-Holm correction).