Natural cytotoxic activity against cytomegalovirus-infected target cells following marrow transplantation

Forty-five patients at high risk for cytomegalovirus (CMV) infection were studied during the first 100 days after marrow transplant to determine the relationship between cytotoxicity against CMV-infected HLA-mismatched target cells and CMV infection. Peripheral blood lymphocytes (PBL) from 35 patients who developed CMV infection had significantly lower cytotoxicity against CMV-infected targets 20-40 days transplant compared with PBL from normal controls (P = 0.003). Responses by PBL from 10 uninfected transplant recipients were not significantly decreased. The PBL that lysed CMV targets had phenotypic and E-rosetting characteristics consistent with natural killer cells. Cytotoxicity against CMV-infected targets by PBL from patients with acute graft-versus-host disease (GVHD) was reduced 20-40 days after transplant compared with responses by patients without GVHD (P = 0.04). Survival from CMV infection was longer in patients whose PBL had greater than or equal to 15% lysis of CMV-infected targets during the first 20-60 days after transplant (P = 0.04). This study suggests that natural cytotoxicity of CMV targets is an important correlate of the acquisition and outcome of CMV infection after marrow transplant.