Cytomegalovirus Infection

Cytomegalovirus (CMV) infection caused by platelet transfusions has been a substantial cause of morbidity and mortality in immunocompromised patients with cancer. Patients who receive allogeneic bone marrow/progenitor cell transplantation are at risk for contracting the virus present in blood products because of cytotoxic preparative regimens, immunosupressive (cyclosporin and corticosteroid) therapy or graft-vs-host disease (GvHD) (14). Up to 60% of this patient population will become infected with CMV, and 50% will have CMV disease if no pre-emptive therapy is given. The risk of CMV infection ranges between 28 and 57% for patients receiving a bone marrow transplant and who are seronegative and receive standard blood products (15). Even with CMV-negative blood products, CMV seroconversion has been reported in 1-4% of CMV-negative donor-recipient transplant patients (16). A recent analysis of our own program identified CMV viremia in only 2.5% (1 of 39) of CMV-negative donor-recipient pairs undergoing allogeneic PBPC transplantation (17). Our analysis included 59 patients undergoing allo-geneic PBPC transplantation in an investigational study of prophylactic granulocyte infusions from stem cell donors. Notably, results showed that CMV-positive granulocytes did not alter the risk of viremia compared with CMV-negative granulocytes (34.5% vs 26.6% incidence of CMV viremia, respectively [95% CI 0.47-4.41]).

CMV infection and CMV disease are much less common than other virally transmitted diseases in patients undergoing conventional chemotherapy or autologous bone marrow/progenitor cell transplantation (18) and are not a significant clinical problem except with CD34+-selected or T-cell depleted progenitor cell transplantations (19).

A randomized, controlled clinical trial (15) in patients receiving allogeneic bone marrow transplants compared CMV-seronegative blood products with unscreened blood products that were subjected to bedside leukofiltration. Four (1.3%) of 252 patients in the CMV-seronegative cohort developed CMV infection, with no CMV disease or fatalities; 6 (2.4%) of 250 patients who had bedside leukofiltration developed CMV disease, and 5 of these patients died. Patients who had leukofiltration had an increased probability of developing CMV disease by d 100 (2.4% vs 0%, p = 0.03). Even when investigators eliminated CMV infections occurring within 21 d of transplantation, two patients in the leukofiltration cohort and none in the seronegative cohort died of CMV disease (20). The investigators' conclusions that leukoreduced blood products are CMV-safe remain controversial (21). In a consensus conference held by the Canadian Blood Service (20), 7 of 10 panelists concluded that patients considered at risk for CMV disease should receive CMV-negative products, even when blood components are leukoreduced.

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