Treg cells prolong skin and heart grafts survival after different CD47 genotype donor specific splenocytes pretreatment

Abstract

Objective To explore the role of regulatory T cells (Tregs) in skin and heart grafts survival prolongation after different CD47 genotype donor specific splenocytes pretreatment. Methods Mouse skin plus hearts transplantation model was set up by using C57BL/6 as recipients and MHC class I-mismatched bm1 as donors.In CD47-/-DST group, recipients received CD47-/-bm1 splenocytes transfusion at 7th d before transplantation. In CD47+ /+ DST group, recipients received CD47+ /+ bm1 splenocytes transfusion at 7th day before transplantation.In control group, recipients only received bm1 skin and heart grafts.The populations of Tregs were analyzed by FACS and immunohistochemistry, respectively.The inhibitory effect of Tregs and anti-donor T cell responses was assessed by MLR. Results Result As compared with control group, the survival time of skin grafts in CD47-/-DST group was slightly longer than in non-DST group (20 days vs.17.5 days, P>0.05), but skin grafts had long-term survival in CD47+ /+ DST group (46.5 days, P 0.05), but heart grafts had long-term survival in CD47+ /+ DST group (42.5 days vs.17 days, P 0.05). As compared with CD47-/-DST group, the ratio of Tregs in lymph node cells in CD47+ /+ DST group increased significantly (P<0.01). Compared to CD47-/-DST group and control group, anti donor specific T cell proliferation was decreased in CD47+ /+ DST group at 7th day after transplantation (P<0.05). The inhibitory effects of Tregs were similar among groups. Conclusion CD47 expressed on DST cells plays an important role in grafts survival prolongation.The ratio of Tregs in lymphocytes plays the key role in grafts survival prolongation.but not the number or inhibitory function of single Treg. Key words: T-lymphocytes, regulatory; Skin transplantation; Heart transplantation; Mice; Graft survival