Poor immune reconstitution is associated with symptomatic BK polyomavirus viruria in allogeneic stem cell transplant recipients.

BACKGROUND: BK polyomavirus (BKPyV) infections are known indicators of immune suppression in hematopoietic stem cell transplant (HSCT) recipients; they can lead to hemorrhagic cystitis, ureteral stenosis, renal dysfunction, and prolonged hospital stays. In this study, we determined transplant-associated variables and immune parameters that can predict for the risk of BKPyV viruria. We hypothesized that BKPyV infection is a marker of poor immune recovery.

METHODS: We analyzed all engrafted patients undergoing first allogeneic HSCT at MD Anderson Cancer Center in Houston between January 2004 and December 2012. We evaluated their immune parameters and their transplant-associated factors. BKPyV positivity was defined as BKPyV detection in urine by polymerase chain reaction testing. Cox proportional hazards model, as well as competing risk analysis method using subdistribution hazard models with death as competing risk, were applied to assess risk of BKPyV viruria.

RESULTS: We identified a total of 2477 patients with a median age of 52 years. BKPyV viruria was manifest in 25% (n=629) of the patients. The median time from transplantation to BKPyV viruria development was 42 days among the patients who had BKPyV viruria. On multivariate analysis, tumor type, acute GVHD, chronic GVHD, myeloablative conditioning regimen, cord blood as the graft source, CD3+ , CD4+ , CD8+ , CD56+ , NK counts, and low platelet count were shown to be significantly associated with BKPyV infection. These finding were further confirmed when models incorporating the competing risk of death yielded similar findings.

CONCLUSION: In this study, we report significant associations between BKPyV reactivation following allogeneic HSCT and suppressed immune variables. In addition, this study provides valuable information on the immune status of HSCT recipients as a predictor of BKPyV infections that may in turn help us formulate plans for more effective prevention and treatment of this infection.