Pretransplant BK Virus-Specific T-Cell-Mediated Immunity and Serotype Specific Antibodies May Have Utility in Identifying Patients at Risk of BK Virus-Associated Haemorrhagic Cystitis after Allogeneic HSCT

BK polyomavirus (BKPyV) persists lifelong in renal and urothelial cells with asymptomatic urinary shedding in healthy individuals. In some immunocompromised persons after transplantation of hematopoietic stem cells (HSCT), the BKPyV high-rate replication is associated with haemorrhagic cystitis (HC). We tested whether the status of BKPyV immunity prior to HSCT could provide evidence for the BKPyV tendency to reactivate. We have shown that measurement of pretransplant anti-BKPyV 1 and 4 IgG levels can be used to evaluate the HC risk. Patients with anti-BKPyV IgG in the range of the 1st-2nd quartile of positive values and with positive clinical risk markers have a significantly increased HC risk, in comparison to the reference group of patients with "non-reactive" anti-BKPyV IgG levels and with low clinical risk (LCR) (p = 0.0009). The predictive value of pretransplant BKPyV-specific IgG was confirmed by determination of genotypes of the shed virus. A positive predictive value was also found for pretransplant T-cell immunity to the BKPyV antigen VP1 because the magnitude of IFN-γ T-cell response inversely correlated with posttransplant DNAuria and with HC. Our novel data suggest that specific T-cells control BKPyV latency before HSCT, and in this way may influence BKPyV reactivation after HSCT. Our study has shown that prediction using a combination of clinical and immunological pretransplant risk factors can help early identification of HSCT recipients at high risk of BKPyV disease.

Risk factors for and prognosis of hemorrhagic cystitis after allogeneic stem cell transplantation: retrospective analysis in a single institution

Hemorrhagic cystitis (HC) is a major complication after allogeneic stem cell transplantation (allo-SCT) and can be life threatening. To analyze risk factors and prognosis, we retrospectively reviewed 249 cases receiving allo-SCT in our institution. Median age was 47 years (13-72 years). Disease status at SCT was progressive in 73 cases. Conditioning was myeloablative (MAC) in 146 cases. Acute graft-versus-host disease (aGVHD) grade II-IV treated with prednisolone occurred in 82 cases, and cytomegalovirus (CMV) was reactivated in 91 cases. HC was reported in 47 cases at a median of 35 days (7-469 days) after SCT, and 34 (72.3%) cases recovered after a median of 19.5 days (2-252 days). In univariate analysis, the identified risk factors for HC included age over 45 years, progressive disease status, MAC, aGVHD treated with prednisolone, and CMV reactivation. In multivariate analysis, older age, MAC, and CMV remained independent predictors (hazard ratios: 2.35, 3.50, and 2.87). In patients with severe HC, percentage recovery was lower (3 in 13 cases; 23.1%) and the median duration was longer (54 days) than in those with moderate HC (31 in 36 cases; 86.1%, 17 days, P < 0.01). Treatment-related mortality was also higher (59.1%, P = 0.03) and overall survival was poorer (16.7%, P < 0.01) at 1 year after SCT. Prospective studies should be started considering prophylactic antiviral administration in high-risk patients such as those identified in this study.