COMPLICATIONS - INFECTIONS

J.C. Calle¹, C. Franco palacios¹, L. Cornell², L. Langman³, B.S. Pritt², M.D. Stegall⁴, M. Prieto⁴, F. Cosio⁵, H. Amer^1
1Nephrology And Hypertension, Mayo Clinic, Rochester/UNITED STATES OF AMERICA, ²Laboratory Medicine And Pathology, Mayo Clinic, Rochester/MN/UNITED STATES OF AMERICA, ³Laborartory Medicine And Pathology, Mayo Clinic, Rochester/MN/UNITED STATES OF AMERICA, ⁴Of Surgery, Division Of Transplantation, Mayo Clinic, Rochester/UNITED STATES OF AMERICA, ⁵Nephrology, Mayo Clinic, Rochester/MN/UNITED STATES OF AMERICA

Body: Introduction: The goal of this study was to study the relationship between BK viremia and BK nephropathy in kidney transplant recipients receiving T cell depleting vs. non depleting induction agents. Methods: In our program it is routine practice to screen for BK by plasma PCR and to obtain a protocol biopsy at 4 months post transplant. Included in this analysis are 290 kidney transplant recipients transplanted between January 2008 and August 2009. BK nephropathy was diagnosed based on biopsy with in-situ hybridization. Results: Recipient mean ± SD age 49.5 (±16.6) years, 124 (42.8%) females, 265 (91.4%) Caucasian, 241 (83.1%) first transplants, and 72 (24.8%) received a deceased donor kidney. Ninety two (31.7%) patients received basiliximab and 198 (68.3%) the depleting agents thymoglobulin 56.2% or alemtuzumab 11.7%. Tacrolimus levels at one month post transplant were 10.5 ± 1.4 ng/ml. Average tacrolimus levels in months 2-4 were 8.0 ± 2.0. There were no differences in tacrolimus levels between those receiving depleting vs. non depleting agents at 1 and 4 months: 10.4 ± 1.3, 10.4 ± 1.6, 8.2 ±2.1 and 7.6± 1.3 ng/ml respectively (p >0.4 for all comparisons). BK viremia within 4 months of the transplant was present in 71 (24.5%) of patients, 21.7% vs. 25.8% in non-depleting and depleting agent treated recipients respectively (p=0.278). Significant BK viremia defined as >10,000 copies/ml occurred in 42 (14.5%) of patients. There was no difference between those receiving non depleting vs. depleting agents: 15 (16.3%) vs. 27 (13.6%) respectively (p=0.592). Twenty (7%) of all patients developed BK nephropathy. Three (3.3%) of the non depleting agent treated group and 17 (8.7%) of the depleting agent treated group (p= 0.134). Two patients had low levels of BK viremia: 1500 and 3000 copies/ml at the time of diagnosis. Both had received the depleting agent thymoglobulin. Peak viremia within 4 months was no different between depleting and non depleting agent recipients in those with BK nephropathy 75505 ± 41420 and 132606 ± 1594258 copies/ml (p= 0.68 Mann Whitney) or those without BK Nephropathy 129137 ± 1678824 and 37000 ± 221282 copies/ml depleting vs. non depleting (p=0.591 Mann Whitney). Conclusion: This study showed that using protocol and for cause biopsies the use of T cell depleting vs. non depleting agents for induction did not appear to influence the relationship between the level of viremia and the diagnosis of BK nephropathy. The smaller proportion of patients treated with a non depleting agent and the dearth of cases in that group is a limitation of the study.

Disclosure: All authors have declared no conflicts of interest.