부산대학교 도서관

We previously reported that the CD28 CD4 T cell subpopulation was expanded in the kidney allograft patients with long graft survival, although these T cells were rarely found in patients with graft survival <5 yr. To understand the CD28 CD4 T cells in the long-term acceptance of kidney allografts, we examined functions of this population and performed a 4 yr follow up study. Peripheral blood mononuclear cells (PBMC) were obtained from 47 long-term living related kidney allograft recipients. CD28 CD4 and CD28 CD4 T cells purified by cell sorting were analyzed for expression of Vβ repertoire. Donor-specific response was examined in mixed lymphocyte reaction (MLR). A follow up study with long-term kidney allograft patients was performed for 4 yr about the rate of CD28 CD4 T cells. Eleven patients were examined by MLRs against donors and third party. Four patients with a marked increase of CD28 CD4 T cells showed the donor-specific responses appeared to be lower when compared with third party-specific responses. Freshly sorted CD28 CD4 T cells showed a restricted Vβ repertoire, whereas the Vβ usage of CD28 CD4 T cells from the same patients was much diversified. Such difference in Vβ repertoire was not evident between the two populations from healthy control. A follow up study showed the ratio of CD28 CD4 T cells appeared to be lower in patients who were suspected of chronic rejection. These unusual CD4 T cells might be related to the long-term acceptance of human transplant allografts.