Kinetics of the liver resident NK cell compartment

Abstract The presence of tissue-resident NK (trNK) cells in the liver has only recently been appreciated. While the role of conventional NK cells (cNK) has been well-characterized, the trNK cell function is only beginning to be elucidated. Using the MCMV model of infection, we found that in contrast to liver cNK cells, trNK cells initially undergo a contraction phase followed by a recovery phase to homeostatic levels. The contraction phase is independent of the virus itself as a similar phenotype is observed following Poly I:C/CpG or α-GalCer injection. Interestingly, this initial contraction phase is independent of other liver lymphocyte subsets as it occurs even in infected lymphopenic animals, suggesting it is provoked by the inflammatory milieu. We also found that the contraction phase is partially due to cell apoptosis while the recovery phase occurs via proliferation in situ. These findings underscore the unique homeostatic properties and kinetics of liver resident NK cell compartment.