Immunomodulation Following Transfusion

Overview

This study is designed to provide information on patients' immune response after exposure to transfused blood. Blood transfusions may have opposite immune effects on patients. One is sensitization. The other is immunosuppression. The magnitude of these effects in patients who are not on chemotherapy is unknown. These effects are thought to be due largely to white blood cells present in the transfusion product. "Leukofiltration" and "gamma-irradiation" are the special treatments that deplete white blood cells. A combination of leukofiltration and gamma-irradiation pretreatment of donor blood is thought to deplete the white blood cells most effectively. In this study, patients scheduled for cardiac surgery are randomly assigned to receive blood products pretreated in one of three ways: untreated, filtered or filtered and irradiated. If their physician orders transfusions, they will receive products assigned to their group. Patients are asked to provide two blood samples during the 4 weeks after surgery. Studies will measure changes in antibody to HLA and in cells that regulate the immune response. The levels of sensitization and immunosuppression will be correlated to the transfusion products received.

Blood transfusions may have opposite immune effects on patients. One is sensitization. The other is immunosuppression. The magnitude of this problem in patients who are not on chemotherapy is unknown. Of patients who do receive donor blood, 50-90 percent become sensitized (make antibody) to HLA proteins present on white blood cells in the donor blood. This is an undesired effect in patients who need an organ or stem cell transplant, as it increases the risk of rejection. Another effect of receiving a blood transfusion, immunosuppression, causes a decreased immune response that compromises patients' ability to fight off infection or tumor cells. These effects - sensitization and immunosuppression - are thought to be due largely to white blood cells present in the transfusion product. Doctors order specially pretreated blood transfusions that have been depleted of white blood cells with the aim of minimizing risks in an "immunocompromised" patient. "Leukofiltration" and "gamma-irradiation" are the special treatments that deplete white blood cells. A combination of leukofiltration and gamma-irradiation pretreatment of donor blood is thought to deplete the white blood cells most effectively. Therefore, blood is pretreated both ways before it is given to patients who need a stem cell transplant or others who are immunosuppressed. Sometimes the pretreated leukofiltration and gamma-irradiated blood is used for "regular" patients who are not immunocompromised so the blood is used before it expires and not wasted. However, doctors do not know for sure whether these expensive pretreatments are really beneficial for "regular" patients such as those undergoing cardiac surgery and whether they would change the risk of developing sensitization or immunosuppression. In this study, patients are randomly assigned to receive blood products pretreated in one of three ways: untreated, filtered or filtered and irradiated. If their physician orders transfusions, they will receive products assigned to their group. Patients are asked to provide two blood samples during the 4 weeks after surgery. Studies will measure changes in antibody to HLA and in cells that regulate the immune response. It is unknown which treatment (leukofiltration with or without gamma-irradiation compared to no pretreatment) is most beneficial in patients who are not immunosuppressed. This study is designed to provide information on patients' immune response after exposure to transfused blood. This information may be useful to caring for patients in the future who require transfusion for cardiac surgery.