The liver natural killer cells tolerate Alemtuzumab induction therapy in humans (126.3)

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Abstract Liver natural killer (NK) cells play a role in both graft acceptance and rejection in liver transplantation (LT). T cell depleting strategies have become an integral part of immunosuppressive regimens widely used for induction in transplant. Alemtuzumab (AL) is a recombinant humanized monoclonal antibody against human CD52. We observed early large granulocyte reconstitution in LT with AL. However, information is limited regarding the phenotype and function of NK cells in T cell depletion using AL. To investigate the role of NK cells in AL induction, we examine the phenotype and function of human NK cells derived from LT recipients and cadaveric donors. Absolute counts of T cells remained low for 6 months. In contrast, those of NK cells had emerged with larger number since early days after LT. Liver (n=7) contained high percentage of CD52-CD56+ NK cells (54.2 ± 9.0 % especially CD56 bright 81.2 ± 5.7 %), which suggested these NK cells could endure treatment of AL. It was statistically significant higher percentage than that of peripheral blood, spleen, and lymph nodes (25.1%, 28.4%, and 9.3 % respectively, P<0.05). Donor liver NK cells had stronger cytotoxicity after IL-2 stimulation in the presence of AL. These data indicated that NK cells in peripheral blood were depleted but NK cells in liver remained alive and active in LT patient with AL induction. These results implicate that liver NK cells play important roles in transplant recipients with AL induction.