Study on the effect of the survival time and the T cells in the discordant heart xenotransplantation produced by intrathymic inoculation with xenogeneic antigen using the model of pig to monkey

Objective: This study was designed to investigate the effect of survival time and T cells on the delayed xenograft rejection caused by intrathymic injection of xenogeneic antigen in the discordant cardiac xenotransplantation, and to investigate the possibility of inducing the tolerance for cardiac xenografts. Methods: In this experiment, pig and monkey were, respectively, selected as donor and recipient. Donor and recipient were divided randomly into four groups. In the blank group (group A) recipients didn't accept any treatments but heart xenotransplantation; In the whole body irradiation (WBI) group (group B) 3 Gy (60Co) was received on d30 before transplantation. In the intrathymic injection group (group C) monkeys were pretreated by the intrathymic injection of pig spleen cells (5 x 107) on d21 before transplantation, the other treatments were the same as that in group A. In the irradiation and intrathymic injection group (group D) monkeys were pretreated by WBI and the intrathymic injection of pig spleen cells at the time just as that in group B and group C. In every group, monkeys were performed heterotopic heart xenotransplantation in abdomen in order to observe the survival time of cardiac xenografts. Results: (1) Survival time of donor heart in group D (91.1 ± 22.8 h) was significantly longer than group B(42.56 ± 1.4 h) and group A (35.6 ± 2.2 h) (P<0.01), there was also evident difference between group D and group C (P<0.05). (2) The result of CD4, CD8 testing in peripheral blood have no difference between group B and group D before transplantation (P>0.05). (3) The results of MLR showed that there is significant reduction in group D than in group A and B (P<0.01) when the recipient splenocyte responded to donor stimulator. There was different stimulating effect between in group C and D (P<0.05). Conclusions: (1) In this model, intrathymic inoculation can't influence the percent of CD4+ and CD8+ T cells in peripheral blood, but pretreatment with IT and WBI can induce T cells immune 4 suppression or immune tolerance, that is similar to allotransplantation in the rodent. (2) Pretreatment with IT and WBI can induce T cells immune suppression or immune tolerance. (authors)