ACUTE GRAFT REJECTION OF HUMAN FETAL PANCREAS ALLOGRAFTS USING DONOR-SPECIFIC HUMAN PERIPHERAL BLOOD LYMPHOCYTES IN THE SCID MOUSE1

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Abstract
Transplantation of human fetal pancreas (HFP) is being considered as a potential treatment for insulin-dependent diabetes mellitus (IDDM). Therefore, it is necessary to have an experimental model of HFP-specific allograft rejection in order to understand all the fators that contribute to allograft rejection, and in which to test potential immunomodulatory protocols. The severe combined immunodeficient (SCID) mouse provides such a model. Previously, it has been reported that human allograft rejection can be observed in SCID mice engrafted with human lymphocytes. However, graft rejection is inconsistent and depends on both the number of lymphocytes injected and on the activation state. Here, we describe a model in which SCID mice are injected intraperitoneally with donor-specific lymphocytes generated by an in vitro culture period with irradiated donor splenocytes. Injection of the donor-sensitized PBL results in an acute rejection of HFP allografts (as early as 4 days post-transplant). This model does not require the establishment of chimerism. in the SCID mice, as demonstrated by the lack of detectable human CD45 cells in the peripheral blood of rejecting mice. Allograft rejection was due to human CD4+ and CD8+ cells, as determined by immunohistochemical analysis of graft-infiltrating cells. The advantages of this model include the potential to specifically manipulate either the phenotype of the responding cells or the mechanism in which the responding population is generated. This model can provide a rapid method to test the efficacy of immunomodulatory regimens designed to protect allografts from an acute rejection response.