Immune donors can protect marrow-transplant recipients from severe cytomegalovirus infections

To study the importance of transferred immunity against cytomegalovirus (CMV) in allogeneic, HLA-matched, T-cell-depleted bone marrow transplantation, the incidence, severity, and outcome of CMV infections were studied in 40 CMV-seropositive recipients in relation to the donors' immunity against CMV. There was no significant difference in the incidence of CMV infections between recipients of seropositive (n = 27) and seronegative (n = 13) marrow. However, the incidence of CMV pneumonitis (8/13 compared with 4/27; p < 0.001) and the mortality attributable to CMV infection (6/13 compared with 1/27, p < 0.01) were significantly greater in the group with seronegative donors than in those with seropositive donors. Multivariate regression analysis showed that recipients of seronegative marrow had fifteen-fold greater risk of CMV pneumonitis and a fifty-fold increase in risk of a fatal CMV infection than recipients of seropositive marrow. Thus, after T-cell depletion, CMV-seropositive marrow protects seropositive recipients against severe CMV infections; whenever possible, therefore, such recipients should be given marrow from seropositive donors. Ultimately, active immunisation of CMV-seronegative donors might help to protect seropositive recipients of T-cell-depleted marrow transplants against severe CMV infections.