Bootcongres

Background Although CD8+ T-cell and NK-cell mediated cytotoxicity against renal tubular epithelial cells (TECs) play a crucial role during rejection, the degree of inhibition of these lytic immune responses by immunosuppressive drugs are unknown. We investigated the CD8 T-cell and NK-cell responses induced by TECs in vitro and questioned how these processes are affected by immunosuppressive drugs. Methods Donor-derived TECs were cocultured with recipient PBMC. Proliferation of CD8+ T cells and NK-cell subsets was assessed using PKH dilution assay. CD107a degranulation and europium-release assay were performed to explore CD8+ and NK-cell mediated TEC lysis. Experiments were conducted in absence or presence of tacrolimus (10ng/ml), everolimus (10ng/ml) and prednisolone (200ng/ml). Results TECs induce significant CD8+ T-cell and NK-cell proliferation. All immunosuppressive drugs significantly inhibited TEC-induced CD8+ T-cell proliferation. Interestingly, prednisolone was the most powerful inhibitor of NK-cell proliferation. CD8 and NK-cell mediated early lytic responses were marked by strong degranulation after encounter of unstimulated TECs, represented by a high cell surface expression of CD107a. However, using IFN-γ/TNF-α activated TECs, the NK degranulation response was significantly reduced, and CD8 degranulation response was even more enhanced (P<0.05). TEC-induced CD8 degranulation and CD8 mediated TEC lysis were preferentially inhibited by tacrolimus and prednisolone, and not by everolimus. While tacrolimus showed the most inhibitory effect on degranulation of NK cells, NK-cell mediated TEC lysis was efficiently inhibited by prednisolone (P<0.05). Conclusion Overall, our data point to limited efficacy of immunosuppressive drugs on CD8+ T-cell and NK-cell mediated lysis of human renal tubular epithelial cells.