Association between Polyoma BK Virus Infection and Hemorraghic Cystitis in Allogenic Hematopoietic Stem Cell Transplantation Recipients.

BK Virus (BKV) infection is a common and benign infection occuring in childhood and resulting in viral latency. Because of immunosuppression, acute graft-versus-host disease (a-GVHD), and co infection with other viruses BKV infection often occurs after allogenic hematopoietic stem cell transplantation (HSCT) resulting, in some cases, in hemorraghic cystitis (HC).

We reviewed 258 patients who underwent allogenic HSCT in our institution between january 2001 and december 2005. One hundred and seven patients had a myeloablative conditioning regimen based on cyclophosphomide in combination with either total-body-irradiation (TBI/Cy) or Busulfan (Bus/Cy) with prophylaxis by MESNA. One hundred and fifty-one patients had a Fludarabine based reduced intensity conditioning regimen. BKV was detected by real-time PCR on urinary samples in most cases.

Macroscopic HC occured in 17 patients and BKV was detected in 15 patients out of 17. Among patients with HC and BKV viruria 11 (out of 107) received a conventional regimen compared with only 4 patients out of 151) positive for BKV in the non-myeloablative regimen group.

Although the number of patients is small, these data suggest strongly the role of the myeloablative regimen in the occurence of BKV induced HC. The high immunosuppression level induced by the conditioning regimen and the bladder injuries could explain this high frequency compared with the relative low frequency in patients with the less intensive regimen.

A prospective work is ongoing to better characterize the incidence, risk factors, clinical outcome and management of BKV induced HC after allogenic stem cell transplantation.