Residual plasma in red blood cells and transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is the most common cause of death from blood transfusion and red blood cells (RBCs) now account for approximately 50% of these fatalities. RBCs from female donors have been implicated in large series and HLA Class II antibodies to cognate recipient antigens identified in small series and case reports. The absolute volume of residual plasma in these RBCs is unknown.

Two confirmed cases of RBC-associated TRALI in which the implicated donors had Class II antibodies were investigated, and the antibody strength against recipient cognate antigens was assessed using a fluorescent bead assay. RBCs in additive solution (AS) were studied on Day 42 of liquid storage to calculate residual anticoagulated plasma.

Both RBC units were stored in AS-1 and were from female donors who had anti-HLA Class II antibodies of high strength against cognate antigens in the recipients. Anti-DR4 was identified in both cases. Nineteen AS-1 RBC units manufactured from whole blood donations using a hard spin had a mean (±1SD) residual plasma content of 38 ± 8 mL, and 26 AS-3 RBC units manufactured using a soft spin had 66 ± 13 mL (p < 0.01).

RBCs continue to be manufactured from female donors of unknown or even known anti-HLA status. The residual plasma content of these RBCs may approach 100 mL. A combination of a high-strength antibody and large residual plasma volume could explain severe or even fatal RBC-associated TRALI.