Finally, SELL (CD62L) gene was found to be expressed by mature NK cells with polyfunctionality, which combine the capacity of CD56bright NK subsets to produce INF-γ in response to cytokines and to proliferate in vivo during viral infection, with the cytotoxic ability - typical of CD56dim populations - to kill and produce cytokines upon engagement of activating receptors [37]. This evidence concerns the gene SELL and viral infectious disease.