Immunological aspects of fresh and cryopreserved aortic valve transplantation in rats.
BACKGROUND
The influence of immune activation on valve allograft degeneration remains unclear. We studied the combined effect of major histocompatibility complex (MHC)-incompatibility and cryopreservation on valve performance, histomorphology, and tissue antigenicity in rats.


METHODS
Fresh or cryopreserved allogeneic aortic valves from WAG (RT1u) rats were transplanted to DA (RT1a) recipients and syngenic transplants served as controls. After 7 or 21 days, valves were examined for competence and morphology. Immune reactivity of the recipient was measured by concanavalin A (conA) stimulation and analysis of donor-reactive Helper T-lymphocyte frequencies (HTLf) in peripheral blood and spleen.


RESULTS
Syngenic grafts demonstrated normal competence and structure. Allografts lost their competence over time caused by destruction of the leaflets combined with cellular infiltration in the vascular wall. Cryopreservation induces early loss of competence and retrovalvular thrombosis. Cryopreserved allografts were also heavily infiltrated. ConA stimulation indices and HTLf were higher in allogeneic recipients compared to syngenic recipients (p < 0.03). Cryopreserved allografts elicited a lower immune response compared with fresh allografts (p < 0.03).


CONCLUSIONS
Aortic valve allografts are able to induce a donor-reactive immune response that is related to early graft destruction and incompetence. Cryopreservation appears to diminish but not eliminate the antigenicity of the allograft.
Oei
F B
FB
Department of Cardio-Thoracic Surgery, Heart Valve Bank Rotterdam, The Netherlands. oei@inw1.azr.nl
Stegmann
A P
AP
Vaessen
L M
LM
Marquet
R L
RL
Weimar
W
W
Bogers
A J
AJ
D000818:Animals; D001021:Aortic Valve / Q000276:immunology / Q000473:pathology / Q000637:transplantation; D015925:Cryopreservation; D006084:Graft Rejection / Q000276:immunology* / Q000473:pathology; D006351:Heart Valves / Q000276:immunology / Q000473:pathology / Q000637:transplantation*; D007519:Isoantigens / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D018655:Lymphocyte Count; D008285:Major Histocompatibility Complex / Q000276:immunology; D009926:Organ Preservation; D051381:Rats; D011919:Rats, Inbred Strains; D006377:T-Lymphocytes, Helper-Inducer / Q000276:immunology / Q000473:pathology; D016042:Transplantation, Heterotopic; D014184:Transplantation, Homologous; D014185:Transplantation, Isogeneic
D007519:Isoantigens