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Abstract: PO2190

Regulatory T Cells, BK Virus Infection, and Long-Term Outcomes in Kidney Transplant Recipients

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical

Authors

  • Caliskan, Yasar, Saint Louis University School of Medicine, Saint Louis, Missouri, United States
  • Kiran, Bayram, Kastamonu Universitesi, Kastamonu, Kastamonu, Turkey
  • Kekik, Cigdem, Istanbul Universitesi Istanbul Tip Fakultesi, Istanbul, Istanbul, Turkey
  • Yazici, Halil, Istanbul Universitesi Istanbul Tip Fakultesi, Istanbul, Istanbul, Turkey
  • Senturk Ciftci, Hayriye, Istanbul Universitesi Istanbul Tip Fakultesi, Istanbul, Istanbul, Turkey
  • Dirim, Ahmet Burak, Istanbul Universitesi Istanbul Tip Fakultesi, Istanbul, Istanbul, Turkey
  • Mirioglu, Safak, Istanbul Universitesi Istanbul Tip Fakultesi, Istanbul, Istanbul, Turkey
  • Oto, Ozgur Akin, Istanbul Universitesi Istanbul Tip Fakultesi, Istanbul, Istanbul, Turkey
  • Randall, Henry B., Saint Louis University School of Medicine, Saint Louis, Missouri, United States
  • Savran Oguz, Fatma, Istanbul Universitesi Istanbul Tip Fakultesi, Istanbul, Istanbul, Turkey
  • Turkmen, Aydin, Istanbul Universitesi Istanbul Tip Fakultesi, Istanbul, Istanbul, Turkey
  • Lentine, Krista L., Saint Louis University School of Medicine, Saint Louis, Missouri, United States
Background

Regulatory T cells (Tregs) may inhibit pathogen-specific immunity in infectious disorders. We monitored Treg levels during BK virus (BKV) viremia/viruria, examined pattern of Tregs that might contribute BKV infection, and assessed their prognostic value for the KTx outcomes.

Methods

We evaluated 20 KTx recipients (male:13, mean age:41±12 years, living donor 15) in whom BKV viremia/viruria was detected at a median 12.6 (IQR, 4.6-31.2) months after KTx. Serum and urine BKV DNA were measured by real-time PCR at baseline, 1 and 3 months after detection of BKV viremia/viruria. Lymphocyte profile and CD4(+)CD25(+)FoxP3(+) Tregs were measured by flow cytometry concurrently at these time points. Graft outcomes over 8 years were examined in relation to BK viremia, viruria levels, and lymphocyte profiles.

Results

At the time of diagnosis of BKV viremia/viruria, 17 (85%) patients were on calcineurin inhibitor (CNI)-based triple immunosuppression. CNI was discontinued in 9 patients, sirolimus was started in 3 of them. Mycophenolic acid was switched to azathioprine or the dose was decreased in all patients. Reduction in overall immunosuppression was associated with a decrease in serum and urine BKV DNA levels. Tregs and CD8(+) T lymphocytes were significantly decreased and CD4(+) T lymphocytes were increased during this period (Figure 1). After a median follow-up of 8.1 years (IQR, 3.3-8.5), 6 (30%) patients lost their allografts. There were no significant differences in mean Tregs levels between patients with and without graft failure (p=0.63). Serum and urine mean BKV DNA levels were similar between patients with and without graft failure (p=0.38 and p=0.20, respectively).

Conclusion

Tregs may play a role in BKV infection, reduction in the overall amount of immunosuppression is associated with improvement of BKV viremia/viruria accompanied by a decrease in Treg levels. Future work is needed to discriminate predictors of allograft failure in patients with BK nephropathy.