CLEC2D and infection: Along with other NKRs, LLT1/CD161 interaction seems to fine-tune the responsiveness of NK cells, downmodulating effector responses and being involved in NK cell peripheral self-tolerance, independently of MHC class I. If LLT1 is viewed as a self-ligand not expressed under resting conditions and upregulated upon activation, the level of expression of CD161 also appears to be modulated by infection and inflammation.