Background:

The transcription factor Eomesodermin (Eomes) is critical in the maintenance of antigen-specific memory T cells (Tmem). We have shown previously that prolonged kidney allograft survival in nonhuman primates (NHP) given regulatory dendritic cell infusion was associated with donor-specific Tmem exhibiting low Eomes and high cytotoxic T lymphocyte-associated protein 4 (CTLA4) expression. The role of Eomes in alloreactive Tmem is largely unknown. We characterized the phenotype and function of alloreactive Eomes⁺CD8⁺T cells in healthy humans and naïve rhesus monkeys.

Methods:

Eomes expression by CD8⁺T cells was evaluated by flow cytometry. Eomes negative (neg), low (lo) and high (hi) subpopulations were assessed, before and after anti-CD3/CD28 bead activation or allo-stimulation. Intracellular cytokines (IFNg, TNFa, and IL-2), T-bet, Granzyme B and CTLA4 expression were examined.

Results:

Without activation, mean percentages of Eomes^neg CD8+ T cells were 48.3 and 63.08%, Eomes^lo 19.5 and 22.76%, Eomes^hi 31.67 and 13.45%, in normal human and monkey PBMC respectively.

In humans, Eomes^hi and Eomes^lo populations comprised higher percentages of effector memory T cells while the Eomes^neg subpopulation comprised higher percentages of naïve T cells than in monkeys.

In humans, Eomes^hi and Eomes^lo expressed higher levels of TNFa, INFg (T-bet) and Granzyme B, and lower levels of IL-2 compared to Eomes^neg CD8⁺T cells. In monkeys the expression was similar among Eomes^hi, Eomes^lo and Eomes^neg subpopulations, except for low Granzyme B expression by Eomes^hi and low IL-2 expression by Eomes^lo subpopulations.

Following CD3/CD28 activation or allo-stimulation, two distinct populations of Eomes^lo and Eomes^hi proliferating CD8⁺T cells were observed. In humans, CTLA4 expression was similar in Eomes^lo and Eomes^hi proliferating cells, while in monkeys, Eomes^lo proliferating cells exhibited higher CTLA4 expression.

Following allo-stimulation, human and monkey Eomes^hi proliferating cells expressed low levels of IL-2, but high levels TNFa, IFNg (T-bet), and Granzyme B compared to Eomes^lo proliferating cells.

Conclusions:

We show for the first time that despite similar memory phenotypes of Eomes⁺CD8⁺T cells in humans and NHP, their functions after allostimulation are dissimilar. Furthermore, variable expression of Eomes by CD8⁺T cells following allostimulation may correlate with diverse incidences of alloreactive Tmem in humans and NHP.

CITATION INFORMATION: Perez-Gutierrez A, Lu L, Zahorchak A, Ono Y, Thomson A, Ezzelarab M. Eomesodermin Expression by CD8+ Alloreactive T Cells in Human and Nonhuman Primate Allograft Recipients. Am J Transplant. 2016;16 (suppl 3).

« Back to 2016 American Transplant Congress