title: CD52-Negative NK Cells Are Abundant in the Liver and Less Susceptible to Alemtuzumab Treatment.
abstract: BACKGROUND
  T-cell depleting strategies have become an integral part of immunosuppressive regimens in organ transplantation. Alemtuzumab is a humanized monoclonal antibody against CD52, a cell-surface antigen on several immune cells. It has been suggested that lymphocyte depletion increases the risk of serious infections. However, this has not been observed with short-term alemtuzumab treatment in an organ transplant setting. For induction therapy using alemtuzumab following liver transplantation, we found that T- and B-cell numbers declined rapidly after alemtuzumab therapy; however, the natural killer (NK) cell number was sustained. NK cells are important effectors of innate immunity. Since the effects of alemtuzumab on NK cell functions, especially those of liver NK cells, are unknown, this study aimed to investigate this in detail.
  
  
  METHODS
  To assess the effect of alemtuzumab on NK cells, samples were obtained from 7 organ donors and examined by flow cytometry using Annexin V and propidium iodide. Phenotypical and functional differences within subsets of NK cells with different levels of CD52 expression were determined by flow cytometry and in vitro cytotoxicity assays.
  
  
  RESULTS
  CD52 expression on NK cells was lower than that on other lymphocyte subsets. The liver contained a large number of CD52- NK cells compared with the peripheral blood. In vitro treatment of liver-derived NK cells with alemtuzumab did not result in cell death. In contrast, co-incubation with alemtuzumab induced cell death in peripheral blood mononuclear cells and non-NK cells in the liver. Furthermore, CD52- liver NK cells were more cytotoxic and produced more IFN-γ than CD52+ NK cells after cytokine activation.
  
  
  CONCLUSIONS
  The liver contains a large number of CD52- NK cells. These cells are refractory to alemtuzumab and have robust activity. These findings indicate that CD52- NK cells persist and could protect against infection after alemtuzumab-based lymphocyte depletion.
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Ryuichi
authors: R
authors: Hotta
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.|Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Science, Department of Surgery, Hiroshima University, Hiroshima, Japan.
authors: Masahiro
authors: M
authors: Ohira
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Toshiharu
authors: T
authors: Matsuura
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Izumi
authors: I
authors: Muraoka
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Panagiotis
authors: P
authors: Tryphonopoulos
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Ji
authors: J
authors: Fan
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Akin
authors: A
authors: Tekin
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Gennaro
authors: G
authors: Selvaggi
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: David
authors: D
authors: Levi
authors: Department of Pathology and Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Phillip
authors: P
authors: Ruiz
authors: Cell Transplant Center, Diabetes Research Institute, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Camillo
authors: C
authors: Ricordi
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Rodrigo
authors: R
authors: Vianna
authors: Division of Frontier Medical Science, Programs for Biomedical Research, Graduate School of Biomedical Science, Department of Surgery, Hiroshima University, Hiroshima, Japan.
authors: Hideki
authors: H
authors: Ohdan
authors: Sir William Dunn School of Pathology, Oxford University, Oxford, England, United Kingdom.
authors: Herman
authors: H
authors: Waldmann
authors: Cleveland Clinic Florida, Weston, FL, United States of America.
authors: Andreas G
authors: AG
authors: Tzakis
authors: Division of Liver and Gastrointestinal Transplantation, Department of Surgery, University of Miami Miller School of Medicine, Miami, FL, United States of America.
authors: Seigo
authors: S
authors: Nishida
mesh_terms: D000074323:Alemtuzumab; D000911:Antibodies, Monoclonal / Q000737:chemistry; D061067:Antibodies, Monoclonal, Humanized / Q000627:therapeutic use*; D000912:Antibodies, Neoplasm; D015703:Antigens, CD / Q000378:metabolism*; D000951:Antigens, Neoplasm / Q000378:metabolism*; D017252:CD3 Complex / Q000378:metabolism; D000074301:CD52 Antigen; D016923:Cell Death; D016207:Cytokines / Q000378:metabolism; D004351:Drug Resistance; D005434:Flow Cytometry; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D007694:Killer Cells, Natural / Q000166:cytology / Q000187:drug effects*; D008099:Liver / Q000166:cytology*; D008107:Liver Diseases / Q000601:surgery; D016031:Liver Transplantation; D008212:Lymphocyte Depletion; D014019:Tissue Donors
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000912:Antibodies, Neoplasm; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D017252:CD3 Complex; D000074301:CD52 Antigen; C000613862:CD52 protein, human; D016207:Cytokines; D006023:Glycoproteins; D000074323:Alemtuzumab; D007371:Interferon-gamma