Inactivation of Human White Blood Cells in Red Blood Cell Products Using the MIRASOL® System for Whole Blood.

Transfusion of blood products containing white blood cells (WBC) can result in the induction of immune responses that can negatively impact the recipient. An approach that would mitigate these consequences would be beneficial. Previous studies had shown that exposure of platelet concentrates to light in the presence of riboflavin was able to inhibit immune responses mediated by WBC. To make this protocol more widely applicable the effect of treating whole blood units with riboflavin and varying amounts of light was tested. Human peripheral blood mononuclear cells were purified by Ficoll-Hypaque discontinuous centrifugation from aliquots of nonleukoreduced whole blood units that were untreated or exposed to Mirasol treatment using varying light dosages. Viability and phenotype of treated cells was unchanged compared to untreated controls. The results showed that exposure of whole blood units to 33J/mL red blood cells (RBC) UV light in the presence of riboflavin completely inhibited proliferation of WBC in response to polyclonal stimulators such as phytohemagglutinin, and anti-CD3/CD28 or to allogeneic stimulator cells in a mixed lymphocyte culture (MLC). Additional assays showed that treated WBC were unable to induce proliferation of normal responder cells in an MLC. Treated cells did not produce inflammatory or TH1/TH2 cytokines when stimulated with lipopolysaccharide for 24 hours or anti-CD3/CD28 for 72 hours. In addition, treatment was found to inhibit T cell activation as evidenced by the lack of CD69 expression in treated compared to untreated control cells when incubated with phorbol 12-myristate 13-acetate. These treatment conditions did not induce crossmatch incompatibility. Methemoglobin levels and hemolysis in RBC units stayed below 1% during storage for 42 days in AS-3. Platelet and plasma units separated from whole blood after treatment showed acceptable cell and protein quality over 5 days in storage or as fresh frozen plasma, respectively. In summary, Mirasol treatment was able to functionally inactivate WBC in whole blood products without adversely affecting the quality of the RBC, platelets and plasma. This technique offers potential means to achieve inactivation of WBC in whole blood units that can subsequently be separated into RBC, platelet and plasma components.