Use of a DNAemia cut-off for monitoring human cytomegalovirus infection reduces the number of preemptively treated children and young adults receiving hematopoietic stem-cell transplantation compared with qualitative pp65 antigenemia.

We performed a randomized trial comparing the use of quantitative DNAemia versus positive antigenemia for starting preemptive antihuman cytomegalovirus (HCMV) therapy in hematopoietic stem-cell transplantation (HSCT) recipients. In the DNAemia arm, antiviral therapy was initiated on reaching a DNAemia cut-off of 10 000 DNA copies/mL of whole blood, whereas in the antigenemia arm, therapy was started in the presence of a positive antigenemia. The aim of the study was to compare the number of patients treated in the 2 arms. On the whole, 178 patients (89 in each arm), receiving unmanipulated HSCT from either a relative or an unrelated donor, completed the study. Although the incidence of HCMV infection was comparable in DNAemia and antigenemia arms (34% vs 42%, respectively, P = .259), the number of patients treated was significantly lower in the DNAemia arm (18% vs 31%, P = .026). No patient developed HCMV disease. The use of a DNAemia cut-off avoids unnecessary antiviral treatment.

B lymphocyte reconstitution after hematopoietic stem cell transplantation: functional immaturity and slow recovery of memory CD27+ B cells.

OBJECTIVE: Functional recovery of B lymphocytes after hematopoietic stem cell transplantation (HSCT) can take up to 2 years. HSCT recipients may obtain protective titers of pathogen-specific antibody through vaccination, but optimal timing of reimmunization remains to be defined. PATIENTS AND METHODS: In this study, we evaluated the reconstitution of B-cell number and activity in 139 children given HSCT, by B-cell subset phenotyping and in vitro immunoglobulin (Ig) production. RESULTS: Patients were longitudinally studied at 3, 6, 12, and 18 to 24 months after transplantation. At all time points, recipients displayed a significantly higher percentage of naive (IgD+CD27-) B cells and showed significantly lower production of stimulated in vitro Ig as compared to healthy controls. Moreover, during follow-up, we observed an increase in the proportion of patients who had CD27+ B subsets and who were able to mount in vitro Ig production greater than the 5th percentile. CONCLUSION: Similar to what has been described in adults, most children lack memory B cells and produce low amounts of Ig. However, the number of B cells, as well as their function, gradually recovered over time and the spread of data we observed suggests that the reimmunization schedule should be individualized for each patient. It remains to be defined in a prospective clinical study the time point at which a patient should start reimmunization. A reasonable hypothesis to be explored is the time point at which a percentage of memory B cells greater than the 5th percentile of normal controls is reached.