Graft-versus-host disease (GvHD) presents a major cause for morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Rabbit-derived antithymocyte globulin (rATG) treatment reduces the incidence of GvHD after allogeneic hematopoietic stem cell transplantation. However, delayed immune reconstitution following rATG treatment, partly caused by hampered thymic function, is being discussed. The present study aims at elucidating possible cytotoxic effects of 2 commonly used rATG preparations on cultured human thymic stroma, especially thymic epithelial cells (TECs).
A primary TEC culture was established and the binding and cytotoxicity of 2 rATG preparations to the aforementioned cells were assessed by flow cytometry and immunofluorescence analyses. The release of several cytokines by cultured thymic stroma cells in response to rATG was analyzed via multiplex enzyme-linked immunosorbent assays.
Both preparations showed a comparable dose-dependent binding to TECs and exerted a similar complement-independent, dose-dependent cytotoxicity. rATG exposure further resulted in hampered secretion of interleukin (IL)-7, IL-15, and IL-6, cytokines being involved in thymic T cell development and proliferation. Pretreatment with keratinocyte growth factor diminished rATG-induced cytotoxicity of TECs and restored their IL-7 and IL-15 secretion.
Cytotoxic effects on TECs link the rATG-induced thymic damage to the delayed T cell reconstitution, witnessed after rATG treatment. Our data support a combination treatment of rATG and thymus-protective strategies such as keratinocyte growth factor to simultaneously offer sufficient GvHD prophylaxis and overcome delayed T cell reconstitution caused by thymic damage.
1 Department of Hematology, Oncology and Tumor Immunology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
2 Department of Congenital Heart Surgery, Pediatric Heart Surgery, Deutsches Herzzentrum Berlin, Berlin, Germany.
3 Experimental and Clinical Research Center (ECRC), Berlin, Germany.
4 Institute for Medical Immunology, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.
5 Department of Nephrology and Internal Intensive Care Medicine, Charité-Universitätsmedizin, Berlin, Germany.
6 Berlin-Brandenburg Center for Regenerative Therapies, Berlin, Germany.
7 Berlin-Brandenburg School for Regenerative Therapies, Berlin, Germany.
8 Berlin Institute of Health, Berlin, Germany.
Received 15 December 2018. Revision received 14 April 2019.
Accepted 8 May 2019.
The authors of this manuscript have conflicts of interest to disclose as described by Transplantation. The studies reported in this publication were supported by a grant from Neovii Biotech GmbH. Although a financial conflict of interest was identified for the management based on the overall scope of the project and its potential benefit to Neovii Biotech GmbH, the research findings included in this publication may not be necessarily related to the interests of Neovii Biotech GmbH. The terms of this arrangement have been reviewed and approved by Charité Universitätsmedizin Berlin in accordance with its policy on objectivity in research.
E.M.K. and I-K.N. participated in research design, performed experimental and data analysis, and participated in the writing of the article. M-Y.C. participated in research design and provided human thymic tissue. Y-S.O. performed experimental analysis. L.I.O., S.C.B., and B.G. participated in data analysis. P.R., H-D.V., L.B., and A.T. participated in research design.
Correspondence: Il-Kang Na, MD, Department of Hematology, Oncology and Tumor Immunology, Charité - Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. (email@example.com).