Activated sub-populations of lymphocytes and natural killer cells in normal liver and liver grafts before transplantation.

Aims/Background: The anatomic structure of the liver suggests that it is a place of intense trafficking between intra-hepatic and peripheral blood compartment leukocytes. Furthermore, the liver contains a large number of passenger leukocytes that may play a role in the appearance of donor-type microchimerism after transplantation. In this study, we aimed to define the principal lymphocyte sub-populations contained in donor peripheral blood and liver grafts and in normal liver removed during minimally invasive surgery. Methods. Liver biopsies were taken at the time of vascular clampage during liver extraction from donors in a brain dead state (GI: n=14). Normal liver biopsies were removed during minimaly invasive surgery (GII: n=10). Results: We observed evidence of the presence of lymphocytic activation associated with the two major CD8(+) lymphocyte and natural killer (NK) cell populations in the two groups, with a significant increase in TCR gamma delta-bearing lymphocyte receptors between normal liver and the liver graft. Conclusions: The presence of activated leukocytes in the graft could have a fundamental role in induction of peripheral tolerance. This activation could be the result of a basic immunological response linked to the interaction of T cells and NK cells, and of secondary activation due to stress and the conditions necessary for organ removal from donors in a brain dead state.