Depletion of recipient CD4+ but not CD8+ T lymphocytes prevents the development of cardiac allograft vasculopathy.
BACKGROUND
We have described that chimeric rat hearts bearing recipient-type antigen-presenting cells (APCs) do not reject acutely, but develop cardiac allograft vasculopathy (CAV) in untreated recipients. This suggests that CAV is triggered either by CD8+ direct allorecognition or by CD4+ indirect allorecognition. To determine the allorecognition pathway responsible for CAV in this model, recipients of chimeric hearts underwent either CD8+ or CD4+ T cell depletion.


METHODS
Chimeric hearts were created via bone marrow transplantation in two fully major histocompatibility-mismatched rat strain combinations. DA recipients were thymectomized and treated with Ox8 and Ox38 murine monoclonal antibodies, which deplete CD8+ and CD4+ T cells, respectively. Chimeric PVG hearts bearing DA APCs, abbreviated PVG(DA), were heterotopically transplanted into recipients undergoing thymectomy alone or recipients undergoing thymectomy plus either CD4+ or CD8+ T cell depletion.


RESULTS
PVG(DA) allografts survived 100 days, but developed CAV in thymectomized recipients and in those permanently depleted of CD8+ T cells. In contrast, chimeric hearts transplanted into permanently CD4+ T cell-depleted recipients survived 100 days and demonstrated no evidence of CAV.


CONCLUSIONS
In this specific strain combination, recipient CD8+ T cells are neither necessary nor sufficient for the development of CAV, whereas recipient CD4+ T cells are required for the development of CAV. These findings suggest that CAV is dependent on CD4+ indirect allorecognition and that CD8+ direct allorecognition stimulated by nonprofessional APCs plays a minor role.
Szeto
Wilson Y
WY
Department of Surgery, Division of Cardiothoracic Surgery, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA.
Krasinskas
Alyssa M
AM
Kreisel
Daniel
D
Krupnick
Alexander S
AS
Popma
Sicco H
SH
Rosengard
Bruce R
BR
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D002102:Cadaver; D002908:Chronic Disease; D006084:Graft Rejection / Q000517:prevention & control*; D006085:Graft Survival; D016027:Heart Transplantation / Q000009:adverse effects*; D008212:Lymphocyte Depletion; D008297:Male; D051381:Rats; D014184:Transplantation, Homologous