NCR1 and influenza: We speculate that their observed transient differences in NKp46 expression on CD56dim cells may represent an initial, direct effect of influenza vaccination on these NK cells due to only the HA—NKp46 interaction, whereas the differences that we observe here at the much later time points (months) post-vaccination may be the result of a myriad of in vivo factors released during the ensuing immune response to vaccination—such as the effect of cytokines or other mediators produced by other cells after vaccination on CD56dim cells—that coordinate to cause a second wave of NKp46 downregulation.