INTERLEUKIN-10 AND EPSTEIN-BARR VIRUS-INDUCED POSTTRANSPLANT LYMPHOPROLIFERATIVE DISORDER (1996)

We reported recently on the cancer epidemiology after renal transplantation in the Nordic countries (1). The protocol includes cyclosporine monotherapy (no corticosteroids), a 10-day course of polyclonal antilymphocyte globulin, virus prophylaxis with acyclovir and gancyclovir, and, in case of fine needle aspiration biopsy-proven acute rejection, OKT3 anti-T lymphocyte antibody (2). Using serum samples from four of these patients with post-transplant lymphoproliferative disorder (PTLD), we were able to conduct a retrospective analysis for antibodies against Epstein-Barr virus (EBV) early antigens (IgM and IgG) and late antigens (IgG) (Biotest AG, Dreieich, Germany). Since interleukin (IL)-10 has profound suppressive effects on macrophage and T lymphocyte functions, and because the expression of the EBV open reading frame, BCRF1, generates a polypeptide analogous in structure and bioactivity to natural IL-10 (3), we also measured the serum levels of natural and EBV-encoded IL-10 (vIL-10). A double-sandwich ELISA using rabbit antibodies to purified human rIL-10 was used; the methodology was similar to the one described earlier (4). The inter- and intra-assay coefficients of variation for the concentration range between 30 pg/ml and 2 ng/ml were less than 15%. The ELISA recognizes human natural IL-10 as well as vIL-10 (vIL-10His6 expressed in mouse myeloma cells [5]), but shows less than 0.01% cross-reactivity with other cytokines, including human IL-1α, IL-1β, IL-1ra, IL-6, IL-12, interferon-γ, and tumor necrosis factor-α and -β. Judged from the anti-EBV antibody profiles, patients 1 (female, 9 years old) and 3 (male, 27 years) developed primary EBV infections, and patients 2 (female, 64 years) and 4 (male, 18 years) had reactivated EBV infections. In patients 1, 2, and 3, biopsies showed large numbers of blasts in the grafts after 65, 41, and 49 days (Fig. 1, arrows), and EBV-induced PTLD was diagnosed at graftectomy after 68, 44, and 59 days, respectively. Patients 1 and 2 died shortly after multiorgan failure apparently due to widespread lymphomas. Interestingly, patient 3 was diagnosed only after the finding of repeated but fluctuating levels of IL-10 in the blood (Fig. 1). He eventually showed a clear picture of EBV-induced PTLD involving lung, spleen, liver, and graft. He recovered fully after removal of cyclosporine and acyclovir therapy (see below). Patient 4 developed PTLD 3 years after transplantation with lymphomas of recipient origin in the neck, liver, spleen, along the iliac vessels, and in the two grafts (from both parents). The immunosuppression was abrogated, and he received acyclovir i.v. 750 mg five times per day for 6 months. The lymphomas disappeared over a few months (CT scans), as did the elevated IL-10 levels: 650, 800, <30, <30, <30, and <30 pg/ml after 2, 4, 9, 16, 23, and 29 days, respectively. He now has 8 months of excellent graft function. We believe that these studies suggest an important role of IL-10 and/or vIL-10 in EBV-induced PTLD. If substantiated, this may provide new insight into the pathogenesis of PTLD and introduce new strategies for prevention and therapy of PTLD. Acknowledgments. Drs. K.W. Moore, J. de Vries, Y. Liu, and S. Narula, at DNAX Research Institute for Molecular and Cellular Biology and Scheering-Plough Research Institute, graciously provided IL-10 and vIL-10. Sven Arvid Birkeland1; Klaus Bendtzen2 Department of Nephrology and Tissue Culture Laboratory; Odense University Hospital, Odense; Institute for Inflammation Research TA7544; RHIMA Centre; Rigshospitalet National Hospital; DK-2200 Copenhagen N, DenmarkFigure 1: IL-10 in renal transplantation with EBV-induced PTLD. ▪, Patient 1; •, patient 2; ▴, patient 3. Arrows indicate time of diagnosis of PTLD.