#2207 CD3(+) T cell depletion does not predict short term outcomes in kidney transplant patients

Anti-thymocyte globulin (ATG) is the most frequently agent used for immunosuppression induction therapy after kidney transplantation. The efficacy of the ATG treatment is monitored by peripheral blood CD3(+) T cell counts. ATG dosing can be tailored to reach and keep the target commonly accepted as below 50/μL within the week of transplant. In this study, we investigated the significance of reaching CD3(+) T cell target regarding short term adverse outcomes of biopsy-proved rejection, BK viremia and infection related hospitalization in living donor kidney transplant recipients.

This retrospective observational study was conducted on adult patients who received living donor kidney transplants from January 1, 2015 to October 1, 2022. Demographic, clinical and laboratory information were collected using electronical medical records. The average CD3(+) T cell counts of postoperative first 3 days were calculated. Patients with CD3(+) T cell counts ≤ 50/μL were classified as “Optimally Treated”, while the patients with CD3(+) T cell counts >50/μL were classified as “Suboptimally Treated”. The incidence of biopsy-proven rejection, BK viremia and infection related hospitalization in 6 months following the transplant surgery were compared in these two groups.

Sixty one patients were included in the study. Twenty eight were women and the average age was 39 ± 12.7 years. Average HLA mismatch count was 3.6 ± 1.7. Ten patients were desensitized before kidney transplant. Average ATG dose was 6.8 ± 2.3 mg/kg. Mean average CD3(+) T cell count of postoperative first 3 days were 93.9 ± 87.8/μL. During 6 months of follow up, 34.4% (n = 21) had at least one biopsy proved rejection episode, 21.3% (n = 13) had at least one infection related hospitalization and 11.4% (n = 7) had BK viremia. According to average CD3(+) T cell counts of postoperative first 3 days, 16 patients were in “Optimally Treated” group, whereas 45 patients were in “Suboptimally Treated” group. The patients in both groups had similar mean age, gender distribution, HLA mismatch, pretransplant desensitization status and total ATG doses. In 6 months of follow-up, the patients in “Optimally Treated” and “Suboptimally Treated” groups had no statistically difference in incidence of biopsy-proved rejection, BK viremia and infection related hospitalization.

In our study, we could not find any evidence to confirm the significance of reaching CD3(+) T cell target of 50/μL in first 3 days after transplant surgery regarding short term adverse outcomes of biopsy-proved rejection, BK viremia and infection related hospitalization. The value of CD3(+) T cell monitoring to adjust ATG therapy after kidney transplant surgery is questionable. Thus, in the light of our findings, we do not support the use of CD3(+) T cell counts in optimization of induction therapy with ATG after renal transplantation.