Mireille T.M. Vossen Mi-Ran Gent Jean-Claude Davin Paul A. Baars Pauline M.E. Wertheim-van Dillen Jan F.L. Weel Marijke T.L. Roos Debbie van Baarle Jaap Groothoff Ren& A.W. van Lier Taco W. Kuijpers zyxwvutsrqp Received: 29 January 2003 Revised: 14 May 2003 Accepted: 16 June 2003 Published online: 2 December 2003 zyxwvuts 0 Springer-Verlag 2003 M.T.M. Vossen zyxwvutsrqpo (IXI) . M.-R. Gent P. A. Baars . R. A. W. Baars R. A. W. van Lier Department of Experimental Immunology, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands E-mail: m.t.vossen@amc.uva.nl Tel.: + 31-20-5667688 Fax: +31-20-5669756 M.T.M. Vossen . M.-R. Gent . J.-C. Davin J. Groothoff. T. W. Kuijpers Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands P.M.E. Wertheim-van Dillen . J.F.L. Weel Department of Clinical Virology, Academic Medical Center, Amsterdam, The Netherlands M.T.L. Roos . D. van Barrle Department of Clinical Viro-Immunology, Sanquin Research at CLB, Amsterdam, The Netherlands zyxwvutsrqp Spontaneous outgrowth of EBV-transformed B-cells reflects EBV-specific immunity in vivo; a useful tool in the follow-up of EBV-driven imm uno pro1 ifera t ive disorders in a I lograft recipients Abstract During immunosuppres- sive medication, Epstein-Barr virus (EBV) infection is associated with a risk of developing posttransplant lymphoproliferative disease (PTLD). The appropriateness of a spontane- ous EBV B-cell transformation (SET) assay as a monitor of EBV- specific immunity was evaluated to investigate if it safely allows reduc- ing immunosuppressive medication, thereby decreasing the risk of developing PTLD. PBMC were iso- lated longitudinally from 20 pediat- ric renal allograft recipients treated with prednisone and cyclosporine combined with either azathioprine or mycophenolate mofetil. Most significantly, EBV-peptide-specific CD8+ T cells were detectable in the blood of patients with negative SET assays, coinciding with significantly lower EBV loads, whereas these cells were less frequent in the blood of patients with positive SET assays. Reducing the levels of immunosup- pression resulted in normalization of the SET assays. Therefore, the SET assay is a reflection of the interaction between viral replication, transformation of B cells, and EBV-specific immunity in vivo and hence a valuable screening test for EBV-driven lymphoproliferative phenomena in allograft recipients. Keywords Epstein-Barr virus . Transplantation . Immunosuppres- sion . CD8+ T cells . Posttransplant lymphoproliferative disorder Abbreviations zyxw ALP Alkaline phos- phatase . zyxw AZA Azathioprine . B-LCL B cell lymphoblasts . CMV Cytomegalovirus . CTLs Cytotoxic T lymphocytes . EA Early antigen . EBNA Epstein-Barr virus-encoded nuclear antigen . EBV Epstein-Barr virus . ELZspot Enzyme-linked immunospot assay . HSV Herpes simplex virus . MMF Mycophenolate mofetil . PHA Phytohemagglutinin . PTLD Posttransplant lymphoproliferative disease . SFU Spot forming units . SET Spontaneous EBV B-cell transformation . VCA Viral capsid antigen * VZV Varicella-zoster virus Most significantly, the introduction of the immunosup- pressive agent cyclosporine has led to the increased success of allograft function over longer time ranges. Intensified use of immunosuppression has however concomitantly resulted in an increase of the compli- Introduction The remarkable improvement in the survival rates of solid organ transplant patients is to a large extent due to the increased use of immunosuppressive medication.