OBJECTIVETo study the potential relationship between HHV-6 activation and acute graft-versus-host disease (aGVHD) after allogeneic hematopoietic cell transplantation (HSCT).

METHODSPeripheral blood samples were collected before and weekly after HSCT from 72 consecutive recipients. HHV-6 DNAemia was monitored by nested polymerase chain reaction (PCR). The genotypes of HHV-6 were identified by Hind III restriction assay.

RESULTSOf the 72 patients, HHV-6 DNAemia were detected in 45 (62.5%) on a median of day 14 (range, 7 - 63 days) after HSCT. Grade I - IV aGHVD occurred in 40 (55.6%) on a median of day 26 (range, 9 -73 days). The median onset time of HHV-6 DNAemia was significantly earlier than that of aGHVD (P = 0.018). Compared with that in HHV-6 DNAemia negative [HHV-6(-)] patients, the cumulative incidence of grade I - IV aGHVD was higher (68.9% vs. 33.3% , P = 0.003) in HHV-6 (+) patients. Cumulative incidence of grade II - IV aGVHD in HHV-6 (+) cohort was also higher than that in HHV-6 (-) cohort (35.6% vs 14.8% , P = 0.027). Cumulative incidence of grade I - IV aGVHD was higher in patients with both HHV-6 and CMV positive (CMV+/HHV-6+) than in those with either CMV (CMV+/HHV-6-) or HHV-6 positive (CMV+/HHV-6+) and neither of them positive (CMV-/HHV-6-) [78.9% (30/38), 55. 6% (5/9) , 14. 3% (1/7) and 22. 2% (4/18), respectively, P = 0. 0001]. Cumulative incidence of grade II - IV aGVHD in CMV+/HHV-6+ group was also higher than that in CMV+/HHV-6-, CMV-/HHV-6+ and CMV-/HHV-6- groups [42.1% (16/38), 22.2% (2/9), 0% (0/7) and 11.1% (2/18), P = 0. 008].

CONCLUSIONSPatients with HHV-6 activation or HHV-6/CMV co-infection maybe involved in the occurrence of aGVHD after HSCT.