Kidney Week

Abstract: TH-PO842

CD8+ T Cells and Subpopulations as Potential Predictors for Cytomegalovirus (CMV) Viremia in Kidney Transplantation

Session Information

• Transplantation: Clinical - I
  November 02, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Transplantation

• 2102 Transplantation: Clinical

Authors

• Schuller, Max, Medizinische Universitat Graz, Graz, Steiermark, Austria

Max Schuller,

• Mooslechner, Agnes Anna, Medizinische Universitat Graz, Graz, Steiermark, Austria

Agnes Anna Mooslechner,

• Kloetzer, Konstantin A., Medizinische Universitat Graz, Graz, Steiermark, Austria

Konstantin A. Kloetzer,

• Eller, Philipp, Medizinische Universitat Graz, Graz, Steiermark, Austria

Philipp Eller,

• Eller, Kathrin, Medizinische Universitat Graz, Graz, Steiermark, Austria

Kathrin Eller,

Background

CMV viremia is associated with reduced graft survival in kidney transplant recipients, despite potential prevention by antiviral prophylaxis. Identification of patients at risk remains a key challenge in transplant nephrology. Here, we examined the predictive value of pretransplant CD8⁺ T cell subtype immunophenotyping on CMV viremia after transplantation.

Methods

Flow cytometric analysis of peripheral blood leukocytes and CD8⁺ T cell subpopulations was performed shortly before transplantation (timepoint V1) in 65 kidney transplant recipients. CMV viremia was defined as above 100 CMV copies/ml in at least one PCR during the first year of transplantation.

Results

CMV viremia (CMV+) was frequent (n= 33, 50.8%) in our cohort. After one year, eGFR was worse in CMV+ compared to CMV- patients (1.66 vs. 1.25ml/min/1.73m², p<0.001), underlining its detrimental effect on graft function.
Overall, pre-transplant frequencies of CD3⁺CD8⁺ in lymphocytes (19.7% vs. 15.4%, p=0.05) and FoxP3⁺CD25⁺ in CD3⁺CD8⁺ T cells (1.45% vs. 0.74%, p<0.01) were significantly higher in CMV+. Absolute numbers of leukocytes (4145/µl vs. 5249/µl, p=0.01), granulocytes (2576/µl vs. 3317/µl, p=0.01) and monocytes (222/µl vs. 315/µl, p=0.01) were lower in CMV+.
Although not generally regarded as risk factor, women were disproportionally affected by CMV in our cohort (16 CMV+ in 25 women, 64% vs. 17 CMV+ in 40 men, 42.5%). Although we are limited by a small sample size, we sought to explore potential sex-specific risk factors for CMV within the peripheral blood at V1: For men, CD3⁺CD8⁺ T cells were increased in those who latter developed CMV viremia (21% vs. 15.2%, p=0.04). FoxP3⁺CD25⁺ in CD3⁺CD8⁺ T cells were elevated (1.19% vs. 0.71%, p=0.01), and monocytes (211/µl vs. 358/µl, p=0.02) were decreased in women, who became CMV+.

Conclusion

Pre-transplant predictors of CMV viremia within the peripheral leukocyte and CD8⁺ T cell pool may aid in selecting patients for antiviral prophylaxis. While CD8⁺ T cells are generally regarded as cytotoxic, expansion of regulatory subtypes like FoxP3⁺CD25⁺CD8⁺ T cells may render individuals susceptible to infections. Our findings further hint towards sex-specific differences in immune cell abundance and function, which ought to be confirmed in a larger cohort.

Funding

• Commercial Support – Chiesi