ABSTRACT
To induce immune tolerance in recipient rats of allogenic heart transplantation with hydrocamptothecin (HCPT) and cyclosporin A (CsA) and to study the mechanisms of the tolerance, inbred SD rats were chosen as heart donors and Wistar rats as recipients. After transplantation, the recipients were treated with HCPT and/or CsA. The level of cytokine expression was assessed using RT-PCR. The results showed 3 of 10 heart grafts in group C (HCPT 2. 0mg) and 5 of 10 in group E (HCPT+CsA) survived longer than 730 days even immunosup-pression agents (HCPT and CsA) were withdrawn on day 60 after transplantation. Immune tolerance was verified by challenge with SD and SHR rat skin. The levels of IL-2 and IFN-? rnRNA expression were significantly lower in the grafts of tolerant rats than in those of rejected rats, The levels of IL-4 and IL-10 mRNA were significantly higer in the grafts of tolerant rats than in those of rejected rats. The level of cytokine mRNA expression in the grafts was similar to that in spleen of recipients. Our conclusions is high or low dosage of HCPT combined with CsA could induce tolerance in allogenic heart transplantation in rat recipients. Cytokine deviation is one of the mechanisms in allogenic heart transplantation immune tolerance induced by hydrocamptothecin.