Background: The elderly are known as the population with compromised
immunity. In this study we looked for biological markers that distinguish elderly recipients less prone to reject allogeneic kidney grafts and could possibly help finding a group in whom reduced immunosuppression can be administered.
Material/Methods: We have analyzed 18 pairs of kidney transplant recipients
from the same donors. Each pair consisted of an old (ERP) and young (YRP) recipient, age ≥60 or <60, respectively. Peripheral blood CD4 and CD8 T-cells were examined for the length of telomeres, the proportion of naïve (Tn) and memory (central memory and effector memory) subsets and the percentage of functional CD28 cells. Mixed lymphocyte reaction with allogeneic stimulators and anti-CD3/CD28 beads was performed as functional test. Both, ERP and YRP were divided according to the onset of acute rejection (AR) in the past.
Results: History free of AR in ERP was associated with impaired condition of
CD4 T compartment (short telomeres and decreased proportion of CD28 T
cells). In contrary, rejecting ERP kept preserved telomere length and significantly higher number of functional CD28 cells within CD4 T subset. AR in YRP was different as it was associated with increased percentage of CD8 CD28- T-cells, mainly in antigen-experienced effector memory subsets.
Conclusions: The feature that made the elderly less responsive to allogeneic kidney graft was the immunosenescence of CD4 T cells. Rejection in ERP seemed to be associated with both preserved telomere length and significantly higher number of functional CD28 CD4 cells, whereas in YRP AR was
associated with increased level of CD8 CD28- T cells within differentiated
memory cells, which is the feature of clonal expansion of CD8 T cells.

Keywords: Kidney Transplantation