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* Instituto de Biologia Molecular e Celular, Porto, Portugal;
Instituto de Ciências Biomédicas Abel Salazar, Porto, Portugal;
Centro de Investigação em Ciências da Saúde, Instituto Superior de Ciências da Saúde-Norte (ISCSN), Cooperativa de Ensino Superior Politécnico Universitário (CESPU), Portugal; and
University Clinic of Düsseldorf, Institute for Transplantation Diagnostics and Cell Therapeutics, Düsseldorf, Germany
Human intrahepatic lymphocytes are enriched in CD1d-unrestricted T cells coexpressing NKR. Although the origin of this population remains controversial, it is possible to speculate that the hepatic microenvironment, namely epithelial cells or the cytokine milieu, may play a role in its shaping. IL-15 is constitutively expressed in the liver and has a key role in activation and survival of innate and tissue-associated immune cells. In this in vitro study, we examined whether hepatocyte cell lines and/or IL-15 could play a role in the generation of NK-like T cells. The results show that both HepG2 cells and a human immortalized hepatocyte cell line increase survival and drive basal proliferation of T cells. In addition, IL-15 was capable of inducing Ag-independent up-regulation of NKR, including NKG2A, Ig-like receptors, and de novo expression of CD56 and NKp46 in CD8+CD56– T cells. In conclusion, our study suggests that hepatocytes and IL-15 create a favorable microenvironment for T cells to growth and survive. It can be proposed that the increased percentage of intrahepatic nonclassical NKT cells could be in part due to a local CD8+ T cell differentiation.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked advertisement in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
1 This work was supported by grants from the American Portuguese Biomedical Research Fund (Inova Grant) and from ISCSN-CESPU (Grants CESPU 1F/05/2005 and CESPU 2F/03/2006). M.P.C. was supported by a fellowship from Fundação para a Ciência e a Tecnologia (SFRH/BD/24396/2005).
2 Current address: Lymphocyte Development Group, Medical Research Council Clinical Sciences Centre, London, U.K.
3 Address correspondence and reprint requests to Dr. Fernando A. Arosa, Instituto de Biologia Molecular e Celular, Lymphocyte Biology Group, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal. E-mail address: farosa{at}ibmc.up.pt
4 Abbreviations used in this paper: KIR, killer Ig-like receptor; APS, amphotericin B/penicillin/streptomycin; CM, conditioned medium; FBSi, inactivated FBS; FSC, forward light scatter; IHH, immortalized human hepatocyte; PI, propidium iodide; SSC, side light scatter.
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