Functional Competence of NK Cells via the KIR/MHC Class I Interaction Correlates with DNAM-1 Expression.

The interaction of inhibitory receptors with self-MHC class I (MHC-I) molecules is responsible for NK cell education. The intensity of DNAM-1 expression correlates with NK cell education. However, whether DNAM-1 expression directly influences the functional competence of NK cells via the KIR/MHC-I interaction remains unclear. Based on allogeneic haploidentical hematopoietic stem cell transplantation, we investigated the intensity of DNAM-1 expression on reconstituted NK cells via the interaction of KIR with both donor HLA and recipient HLA at days 30, 90, and 180 after hematopoietic stem cell transplantation. The reconstituted NK cells educated by donor and recipient HLA molecules showed the highest DNAM-1 expression, whereas DNAM-1 expression on educated NK cells with only recipient HLA molecules was higher than that on educated NK cells with only donor HLA molecules, indicating that NK cells with donor or recipient HLA molecules regulate DNAM-1 expression and thereby affect NK cell education. Additionally, the effects of recipient cells on NK cell education were greater than those of donor cells. However, only when the DNAM-1, NKP30, and NKG2D receptors were blocked simultaneously was the function of educated and uneducated NK cells similar. Therefore, activating receptors may collaborate with DNAM-1 to induce educated NK cell hyperresponsiveness. Our data, based on in vitro and in vivo studies, demonstrate that the functional competence of NK cells via the KIR/MHC-I interaction correlates with DNAM-1 expression in human NK cells.