The composition of intrahepatic lymphocytes: shaped by selective recruitment?

Intrahepatic lymphocytes have a distinct subset composition and phenotype. Compared with lymphoid tissues, the frequency of natural killer (NK) cells, NKT cells and gammadelta T cells among total lymphocytes is increased within the liver, and alphabeta T cells are predominantly effector/memory cells. Divergent hypotheses on the origin of intrahepatic T cells have emerged to explain this; in these hypotheses, either local development or selective recruitment of cells into the liver dominates. This Opinion highlights findings showing that the migratory preferences of lymphocyte subsets reflect their representation within the liver surprisingly well, suggesting that the composition of intrahepatic lymphocytes, in the absence of inflammation, is largely shaped by the dynamics of cell entry and exit into and from the liver.