Successful treatment of relapsed blastic natural killer cell lymphoma with unrelated cord blood transplantation.

The prognosis for blastic natural killer (NK) cell lymphoma is generally dismal. We report a patient who was successfully treated with unrelated cord blood transplantation (UCBT). A 15-year-old boy was diagnosed as having blastic NK cell lymphoma in the cervical lymph nodes. Autologous peripheral blood stem cell transplantation was performed on achieving a complete remission. However, the disease recurred in the bone marrow 6 months later. Chemotherapy induced a second remission and the patient received UCBT with a conditioning regimen consisting of total body irradiation, thiotepa and cyclophosphamide. Chronic GVHD of the lung occurred, but it was well controlled with steroids. At the time of writing, he remains in remission 18 months after UCBT with an excellent performance status. UCBT may be an option for patients with blastic NK cell lymphoma.

A rapid monitoring system of human herpesviruses reactivation by LightCycler in stem cell transplantation.

To establish a practical monitoring system of human herpesviruses reactivation in patients undergoing stem cell transplantation, we developed a new, very rapid, highly sensitive, and quantitative PCR assay for accurate measurement of human cytomegalovirus (CMV), human herpesvirus 6 (HHV-6) and Epstein-Barr virus (EBV) DNA using LightCycler. The LightCycler system revealed that there was a linear correlation in the wide range of viral template DNA at the indicated number of PCR cycles. Peripheral blood cells were collected from 16 patients undergoing stem cell transplantation. The cut-off level of CMV and HHV-6 was assessed as 10(2) copies/microg and that of EBV as 10(3). High numbers of CMV genomes were detected in 3/13 patients after transplant, and reactivation of HHV-6 was frequently seen, whereas none of the patient showed an elevation of EBV genome copies until the end of the observation period. In the present study, the reactivation of beta herpesviruses is associated with the occurrence of thrombotic microangiopathy (TMA) in two patients undergoing allogeneic BMT. Therefore, it may contribute in clarifying the pathological potential of human herpesviruses using a large number of clinical samples. Our results suggest that this system may be useful for monitoring viral reactivation.

Use of real-time PCR to monitor human herpesvirus 6 reactivation after allogeneic bone marrow transplantation.

Reactivation of human herpesvirus 6 (HHV-6) is common following allogeneic marrow transplantation, however, little is known about the immune control and pathogenic potential of HHV-6 infection after transplantation. In order to determine whether reactivation of HHV-6 plays an important role in the development of complications in patients undergoing allogeneic bone marrow transplantation or not, we developed a very rapid quantification of viral DNA using a LightCycler. The amount of viral DNA was determined using a supernatant of a chronically infected cell line [TaY(OK)] which contains a known amount of viral DNA. Peripheral blood cells were collected from 5 patients undergoing allogeneic bone marrow transplantation once before transplant and once per week after transplant for 8-24 weeks. The real-time PCR system revealed that there was a linear correlation in the range of 101 to 105 molecules of reference. Using this system, we have found the presence of non-diagnosed HHV-6 reactivation as well as symptomatic infection, indicating the potential for routine implementation of this technology for laboratory diagnosis of HHV-6 infection. Our study shows that this method of rapid quantification of HHV-6 genomes by the real-time PCR using a LightCycler may be useful not only to understand the reconstitution of the immune system following marrow transplantation but also to manage the care of patients.