High incidence of cytomegalovirus infection after nonmyeloablative stem cell transplantation: potential role of Campath-1H in delaying immune reconstitution.

Nonmyeloablative conditioning is increasingly used for transplantation in a wide range of diseases, but little is known about its impact on the incidence of infections and immune reconstitution. We examined the pattern and outcome of cytomegalovirus (CMV) infections monitored by polymerase chain reaction-based assays and treated preemptively in 101 patients following nonmyeloablative conditioning containing in vivo Campath-1H. Fifty-one patients (50%) had a CMV infection at a median of 27 days after transplantation with a probability of 84.8% in patients at risk of CMV infection. The probability of recurrence of CMV infection before and after 100 days was 53.6% and 46.6%, respectively, and was more common in unrelated donor transplant recipients. All 3 patients who developed CMV disease died of this complication. The 2 patients with late CMV disease had grade III to IV graft-versus-host-disease (GVHD), which occurred de novo in only 4% of patients and in another 10% following donor lymphocyte infusions. The median time to CD4(+) T-cell count more than 200/microL was 9 months in the 48 patients studied. The probabilities of overall survival and nonrelapse mortality at 18 months were 65% and 27.8%, respectively, with no significant difference in survival between CMV-infected and -uninfected patients. The use of Campath-1H appeared to be associated with a low incidence of GVHD but a high incidence of CMV infections and prolonged immune paresis.