KLRC1 and post-transplant lymphoproliferative disease: Although the effect of tacrolimus on the expression of NKG2A has not been investigated in the study by Kim et al., these results suggest that the immunosuppressive treatment could directly contribute to the relative reduction of CD56dimNKG2A+KIR− NK cells in PTLD patients, however, no statistically significant difference could be identified in our current study.