EBV and CMV reactivations after immunosuppression in the refractory and relapse studies. Nearly all patients were seropositive for EBV (A), whereas CMV seropositivity ranged from 60%-80% (B). Of the seropositive patients, EBV reactivation in the rabbit ATG arm was observed in approximately 80%, with median peak copy numbers of approximately 100 000 copies per 106 mononuclear cell (MNC) genome equivalents (C). In the alemtuzumab arm, EBV reactivations were less frequent and the median peak copy numbers were much lower compared with rabbit ATG (C). There was no difference in the likelihood or degree of reactivation after alemtuzumab in the refractory and relapsed studies. CMV reactivations were less common for both rabbit ATG and alemtuzumab, with median peak copy numbers of approximately 1000/mL. Only one patient in the relapsed study had reactivated CMV after alemtuzumab. All reactivations were self-limited and subclinical with prophylactic or preemptive therapies not used in any case. A positive PCR was defined as > 250 EBV copies/106 MNC genome equivalents or > 250 CMV copies/mL of blood.
