title: First experience with the use of a recombinant CD3 immunotoxin as induction therapy in pig-to-primate xenotransplantation: the effect of T-cell depletion on outcome.
abstract: BACKGROUND
  We have previously reported life-supporting kidney xenograft-survival greater than 80 days using a steroid-free antithymocyte globulin (ATG)-based induction regimen (ATG regimen) in a GalT-KO pig-to-baboon thymokidney (TK) model. We evaluated two induction regimens, a newly developed anti-monkey CD3 recombinant immunotoxin (anti-CD3 rIT) and an anti-human CD2 antibody (LoCD2), by assessing T-cell depletion (TCD) and graft survival.
  
  
  METHODS
  Four baboons received anti-CD3 rIT; the time course of TCD was studied in two animals and the other two received GalT-KO TK transplants. Two additional baboons underwent GalT-KO TK transplantation after treatment with LoCD2. All other treatments were identical to previous TCD studies with ATG. TCD was assessed by flow-cytometry; renal function was evaluated by serum creatinine and histology.
  
  
  RESULTS
  Baboons that received the anti-CD3 rIT died from pneumonia or cardiac failure on days 15 and 23. Both animals in the rIT group died with functioning grafts. Thymokidney grafts from baboons treated with the LoCD2 regimen were rejected by day 14. TCD levels in baboons receiving the anti-CD3 rIT regimen were 150 to 250 cells/μL for at least 14 days, whereas baboons receiving the LoCD2 recovered to more than 300 cells/μL by day 7.
  
  
  CONCLUSIONS
  The newly developed anti-CD3 rIT could be a useful TCD agent in baboons. However, optimal dosage, treatment duration, and bioactivity must be studied to avoid side effects. A LoCD2-based regimen was not effective for preventing xenogeneic rejection. Optimal TCD levels less than 250/μL during the induction period seem to be important for success of xeno-thymokidney transplantation.
authors.affiliation: Transplantation Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nishimura
authors.forename: Joseph
authors.initials: J
authors.lastname: Scalea
authors.forename: Zhirui
authors.initials: Z
authors.lastname: Wang
authors.forename: Akira
authors.initials: A
authors.lastname: Shimizu
authors.forename: Shannon
authors.initials: S
authors.lastname: Moran
authors.forename: Bradford
authors.initials: B
authors.lastname: Gillon
authors.forename: David H
authors.initials: DH
authors.lastname: Sachs
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Yamada
mesh_terms: D000818:Animals; D001706:Biopsy; D017252:CD3 Complex / Q000378:metabolism*; D005434:Flow Cytometry / Q000379:methods; D006084:Graft Rejection; D006085:Graft Survival; D000922:Immunotoxins / Q000737:chemistry*; D016030:Kidney Transplantation / Q000379:methods*; D008212:Lymphocyte Depletion; D010215:Papio; D011323:Primates; D013552:Swine; D013601:T-Lymphocytes / Q000276:immunology*; D013997:Time Factors; D014183:Transplantation, Heterologous / Q000379:methods*; D016896:Treatment Outcome
chemical_list: D017252:CD3 Complex; D000922:Immunotoxins