PLoS ONE (Jan 2016)

A Depleting Anti-CD45 Monoclonal Antibody as Isolated Conditioning for Bone Marrow Transplantation in the Rat.

  • Mark D Jäger,
  • Florian W R Vondran,
  • Wolf Ramackers,
  • Tilmann Röseler,
  • Hans J Schlitt,
  • Hüseyin Bektas,
  • Jürgen Klempnauer,
  • Kai Timrott

DOI
https://doi.org/10.1371/journal.pone.0154682
Journal volume & issue
Vol. 11, no. 5
p. e0154682

Abstract

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OBJECTIVE:A monoclonal antibody (mAb) against the leukocyte common antigen CD45 (RT7 in rats) could facilitate bone marrow transplantation (BMT). This study in rats evaluates a depletive rat anti-RT7a mAb as isolated tool for BMT conditioning without using irradiation or any chemotherapeutic / immunosuppressive agent. METHODS:The model used a CD45 di-allelic polymorphism (RT7a/RT7b). The anti-RT7a mAb was intravenously administered to LEW.1W rats (RT1uRT7a) at 5, 10 and 15 mg/kg. 1x10(8) BM cells of MHC syngeneic (RT1u), MHC disparate (RT1l) or MHC haploidentical (RT1u/l) donors were transplanted. All BM donor strains carried the RT7b allele so that their CD45+ cells were not affected by the anti-RT7a mAb. Recipients were monitored for reconstitution and donor-chimerism in blood leukocytes. RESULTS:mAb dosages of 5 or 10 mg/kg were myelosuppressive, whereas 15 mg/kg was myeloablative. Multi-lineage donor-chimerism at day 100 indicated engraftment of MHC syngeneic BM after any used mAb dosage (5 mg/kg: 46+/-7%; 10 mg/kg: 62+/-5%; 15 mg/kg: 80+/-4%). MHC disparate BM resulted in autologous reconstitution after conditioning by 10 mg/kg of the mAb and caused transient chimerism ending up in death associated with aplasia after conditioning by 15 mg/kg of the mAb. MHC haploidentical BM (F1 to parental) engrafted only after conditioning by 15 mg/kg (chimerism at day 100: 78+/-7%). Abandonment of α/β TCR+ cell depletion from BM grafts impaired the engraftment process after conditioning using 15 mg/kg of the mAb in the MHC syngeneic setting (2 of 6 recipients failed to engraft) and the MHC haploidentical setting (3 of 6 recipients failed). CONCLUSION:This depletive anti-RT7a mAb is myelosuppressive and conditions for engraftment of MHC syngeneic BM. The mAb also facilitates engraftment of MHC haploidentical BM, if a myeloablative dose is used. RT7b expressing, BM-seeded α/β TCR+ cells seem to impair the engraftment process after myeloablative mAb conditioning.