title: Healing of long-term frozen orthotopic bone allografts is not affected by MHC differences between donor and recipient.
abstract: BACKGROUND
  The use of bone grafting in orthopaedic surgery has increased dramatically in recent years. However, the degree to which immune responses are important for the survival of the allograft is not fully understood. In particular it remains unclear whether differences in the major histocompatibility complex (MHC) influence incorporation of bone allografts and their subsequent biologic performance.
  
  
  OBJECTIVE
  Therefore, we asked whether isolated mismatch for MHC antigens of deep frozen bone allografts in the long-term causes (1) immune reactions, and whether these reactions have any effect on (2) morphologic features of the graft, (3) radiographic graft healing, and (4) graft strength.
  
  
  METHODS
  We used an established orthotopic tibial segment transplantation technique that allows determination of mechanical strength, histologic evaluation, and immune responses. Tibial segments that had been deep-frozen at -80°C for 1 year were transplanted into 24 PVG (RT1 (c)) rats from either 12 syngeneic donors or 12 MHC congenic donors PVG.1U (RT1 (u)). We determined immune responses using an indirect Coombs reaction and determined graft healing radiographically and mechanically after 6 months.
  
  
  RESULTS
  We detected no alloantibody production to graft MHC-I antigens, and found no differences between syngeneic and MHC mismatched grafts in terms of remodeling with host bone, graft healing, and mechanical strength.
  
  
  CONCLUSIONS
  Mismatches for MHC antigens do not seem to play a decisive role in healing of long-term, deep-frozen bone allografts.
authors.affiliation: Department of Orthopaedics, Oslo University Hospital, Rikshospitalet, 0027 Oslo, Norway. olav.reikeras@rikshospitalet.no
authors.forename: Olav
authors.initials: O
authors.lastname: Reikerås
authors.forename: Finn P
authors.initials: FP
authors.lastname: Reinholt
authors.forename: Severin
authors.initials: S
authors.lastname: Zinöcker
authors.forename: Hamid
authors.initials: H
authors.lastname: Shegarfi
authors.forename: Bent
authors.initials: B
authors.lastname: Rolstad
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D016025:Bone Transplantation; D015925:Cryopreservation; D006085:Graft Survival; D006650:Histocompatibility Testing; D007518:Isoantibodies / Q000097:blood; D008285:Major Histocompatibility Complex / Q000276:immunology*; D016348:Osseointegration; D011859:Radiography; D051381:Rats; D013977:Tibia / Q000000981:diagnostic imaging / Q000276:immunology / Q000473:pathology / Q000637:transplantation*; D013997:Time Factors; D023001:Transplantation Tolerance; D014184:Transplantation, Homologous; D014185:Transplantation, Isogeneic; D014945:Wound Healing
chemical_list: D007518:Isoantibodies