Background. Cytomegalovirus (CMV) infection is a significant cause of morbidity and mortality after allogeneic hematopoietic stem cell transplantation (HSCT). Recipients of T-cell-depleted (TCD) transplants may be more susceptible to CMV infection as a result of the reduction in transferred T cell immunity. We sought to determine the effect of prior donor and patient CMV exposure on the incidence of CMV infection after TCD allogeneic HSCT. Methods. We retrospectively examined CMV antigen testing results in all patients who had undergone CD6+ TCD related and unrelated donor allogeneic HSCT at our institution from 1996 to 1999. All 124 patients who had documented donor and recipient CMV serologies pretransplant and had undergone CMV antigen testing before day +100 posttransplant were included in the analysis. Results. Forty-one percent of seropositive recipients and 1% of seronegative recipients developed evidence of CMV reactivation (odds ratio 54.1, 95% confidence interval [CI] 6.9-424.1, P<0.001). Prior donor CMV exposure did not place seronegative recipients at increased risk of CMV conversion. Multivariable analysis indicated that prior donor CMV exposure significantly reduced the risk of CMV reactivation in seropositive recipients by 81% (odds ratio 0.19, 95% CI 0.04-0.91, P=0.04). Grades II to IV acute graft-versus-host disease (GVHD) was associated with CMV conversion (P=0.04) when seropositive recipients underwent HSCT from CMV-negative donors, but not when the donor was CMV-seropositive (P=0.54). Conclusions. The CMV serology status of the recipient, rather than the donor, was the primary determinant of risk for CMV conversion after TCD allogeneic HSCT. Despite CD6+ T-cell depletion, immunity against CMV seemed to be transferred with the donor graft and protected seropositive HSCT recipients from CMV reactivation.
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