KLRD1 and pachyonychia congenita: Considering that TGF-beta1 is known to induce down-regulation of some activating NK cell receptors, including NKp30 (42), it is likely that the downmodulation of NKp30 observed in low-grade PC patients may be the result of the combined action of soluble B7-H6 (sB7-H6) and TGF-beta1.