Efficacy and safety of anti-CD45-saporin as conditioning agent for RAG deficiency

Published: 7 February 2022| Version 1 | DOI: 10.17632/mjbgkg63m2.1
Marita Bosticardo,
Anna Villa


TITLE: Efficacy and safety of anti-CD45–saporin as conditioning agent for RAG deficiency Maria Carmina Castiello, Marita Bosticardo, Nicolò Sacchetti, Enrica Calzoni, Elena Fontana, Yasuhiro Yamazaki, Elena Draghici, Cristina Corsino , Ileana Bortolomai, Lucia Sereni, Hsin-Hui Yu, Paolo Uva, Rahul Palchaudhuri, David T. Scadden, Anna Villa, Luigi D. Notarangelo. PMID: 32387109 Background: Mutations in the recombinase-activating genes cause severe immunodeficiency, with a spectrum of phenotypes ranging from severe combined immunodeficiency to immune dysregulation. Hematopoietic stem cell transplantation is the only curative option, but a high risk of graft failure and poor immune reconstitution have been observed in the absence of myeloablation. Objectives: Our aim was to improve multilineage engraftment; we tested nongenotoxic conditioning with anti-CD45 mAbs conjugated with saporin CD45 (CD45-SAP). Methods: Rag1-KO and Rag1-F971L mice, which represent models of severe combined immune deficiency and combined immune deficiency with immune dysregulation, respectively, were conditioned with CD45-SAP, CD45-SAP plus 2 Gy of total body irradiation (TBI), 2 Gy of TBI, 8 Gy of TBI, or no conditioning and treated by using transplantation with lineage-negative bone marrow cells from wild-type mice. Flow cytometry and immunohistochemistry were used to assess engraftment and immune reconstitution. Antibody responses to 2,4,6-trinitrophenyl-conjugated keyhole limpet hemocyanin were measured by ELISA, and presence of autoantibody was detected by microarray. Results: Conditioning with CD45-SAP enabled high levels of multilineage engraftment in both Rag1 mutant models, allowed overcoming of B- and T-cell differentiation blocks and thymic epithelial cell defects, and induced robust cellular and humoral immunity in the periphery. Conclusions: Conditioning with CD45-SAP allows multilineage engraftment and robust immune reconstitution in mice with either null or hypomorphic Rag mutations while preserving thymic epithelial cell homeostasis.



Ospedale San Raffaele


Immunology, Transplantation, Immunodeficiency, Viral Infection of Hematopoietic Progenitor Cells