Monitoring of human herpesviruses after allogeneic peripheral blood stem cell transplantation and bone marrow transplantation

Herpesviruses frequently cause serious complications after allogeneic bone marrow transplantation (allo-BMT). Recent studies have shown more rapid imm une reconstitution after allogeneic peripheral blood stem cell transplantat ion (allo-PBSCT) compared with allo-BMT. However, it has not been clarified whether the improved immune reconstitution after allo-PBSCT is associated with a lower incidence of herpesvirus infections. We monitored the emergenc e of Epstein-Barr virus (EBV), cytomegalovirus (CMV), human herpesvirus 6 ( HHV-6) and HHV-7 DNA by a nested-double polymerase chain reaction in periph eral blood leucocytes from 22 allo-BMT and 16 allo-PBSCT patients, Each vir us had an unique temporal profile of detection. HHV-6 DNA was detected most frequently at 3 weeks after transplantation, whereas CMV and EBV DNA were detected later (2-3 months). Detection rates of HHV-6 DNA at 3 and 4 weeks after allo-BMT were significantly higher than those after allo-PBSCT (9/16 v 2/13 at 3 weeks, P< 0.01; 10/21 v 1/15 at 4 weeks, P<0.01). Detection rat es of the other three herpesviruses after the two types of allogeneic trans plantation were not significantly different throughout observation period. Furthermore, detection of HHV-6 DNA within the first 4 weeks was associated with delayed platelet engraftment after both allo-BMT and allo-PBSCT (P<0. 01). These results suggest an advantage for allo-PBSCT over allo-BMT in ter ms of suppression of HHV-6 reactivation and prevention of subsequent compli cations.