Characterization of Immune Phenotypes in Peripheral Blood of Adult Renal Transplant Recipients using Mass Cytometry (CyTOF)

Abstract

Chronic immunosuppressive therapy in transplant patients can be associated with opportunistic infections and risks of cancer development. There is an important need to better measure the immune status of patients in a transplant setting to improve patient monitoring and guide development of appropriate immunosuppressive agents and regimen. In this study, CyTOF was performed to comprehensively characterize the immune differences between 10 renal transplant recipients and 11 age-matched healthy donors, longitudinally over 6 months. Overall, the immune cells of transplant patients showed signs of increased CD8+ T cell activation/differentiation. Higher levels of CD57 on CD8+ T cells were observed. CD8+ T cells and their memory subsets also showed increased production of MIP-1β and IFNγ. Further, CD107a and Granzyme B expression were also increased in CD8+ T cells and CD56hi NK cells, while Tregs had decreased IL-10 production. These changes are consistent with a more stimulated immune system, despite the administration of immune suppressants to the patients. However, there were also some signs of immune suppression in the transplant patients consistent with the treatment regimen. γδT cells showed decreased TNFα and IFNγ expression, while MIP-1β expression was reduced in NKT, CD56hi NK and γδT cells. CD8+ T memory cell subsets also showed decreased expression of IL-2, IL-17 and GM-CSF. This mosaic pattern of functional changes highlights the importance of comprehensive immune monitoring of these patients. Such information will aid in optimizing individual treatment strategies and development of improved immunosuppressants that specifically target overly activated populations.