title: Inbred or outbred? An evaluation of the functional allogenicity of farm sheep used in cardiac valve studies.
abstract: OBJECTIVE
  Cryopreserved allograft cardiovascular tissue elicits a strong cellular and humoral response in recipients; this may accelerate the deterioration of the allograft and complicate future heart transplantation. Juvenile sheep are the standard model for in vivo valve research and have been used to investigate the allogeneic immune response to cardiac valve and vascular tissue transplantation. Studies to date have not considered the extent of allogenicity of sheep used in transplantation studies.
  
  
  METHODS
  Functional allogenicity was assessed by standard one-way mixed lymphocyte reaction assay using peripheral blood mononuclear cells. Responder cells were stimulated with irradiated stimulator cells and cultured at 37 degrees C in 95% air and 5% carbon dioxide for 3, 4, 5, and 6 days. Cultures were pulsed with tritiated thymidine for 24 hours and harvested onto filtermats.
  
  
  RESULTS
  The allogeneic response, measured as counts per minute, demonstrated a bimodal distribution. Fifty-nine (36.9%) of 160 pairs fell within the first peak (counts per minute < 10,000) and were defined as weak responders. The remaining 101 (63.1%) of 160 pairs of animals demonstrated a strong allogeneic response (counts per minute > or = 10,000) that followed a normal distribution.
  
  
  CONCLUSIONS
  More than 1 in 3 pairs of sheep is too closely related to elicit an immune response when cross-reacted. This finding may alter the interpretation of studies that base their findings on allogeneic transplantations in sheep without ascertaining the genetic similarities of the animals. Valve transplantation studies in a sheep model should assess the extent of allogenicity of donor and recipient sheep.
authors.affiliation: Department of Surgery, University of Alberta, Edmonton, Alberta, Canada. elehr@ualberta.ca
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Lehr
authors.forename: Gina R
authors.initials: GR
authors.lastname: Rayat
authors.forename: Leena S
authors.initials: LS
authors.lastname: Desai
authors.forename: James Y
authors.initials: JY
authors.lastname: Coe
authors.forename: Greg S
authors.initials: GS
authors.lastname: Korbutt
authors.forename: David B
authors.initials: DB
authors.lastname: Ross
mesh_terms: D000818:Animals; D015925:Cryopreservation; D016027:Heart Transplantation; D006351:Heart Valves; D007959:Lymphocyte Culture Test, Mixed; D023421:Models, Animal; D012756:Sheep; D014181:Transplantation Immunology / Q000276:immunology*; D014184:Transplantation, Homologous / Q000276:immunology*