RESUMEN
<p><b>OBJECTIVE</b>To explore the correlation between the polyomavirus DNA load and the dose of immunosuppressant in patients with allogene bone marrow transplantation (allo-BMT) for preventing the development of post-transplantational hemorrhagic cystitis.</p><p><b>METHODS</b>Serial blood and urine samples from 122 cases of allo-BMT recipients were obtained and DNA was extracted from urine samples. Polyomavirus DNA-specific probe was synthesized and Fluorescence quantitative polymerase chain reaction was used for detecting the polyomavirus DNA loads and Fluorescence polarization immunoassay (FPIA) was performed for determining the dose of immunosuppressant Cyclosporin A (CsA) in blood.</p><p><b>RESULTS</b>The altered polyomavirus DNA load in urine was followed by concentration of CsA in blood. When the concentration of CsA in blood was higher than 86-105 ng/ml, the positive rate of polyomavirus DNA load was significantly increased and both presented the linable correlation.</p><p><b>CONCLUSION</b>In immunosuppression condition, polyomavirus DNA load correlated to the dose of immunosuppressant, which increased the risk of post-transplantational hemorrhagic cystitis.</p>