HLA and RBC immunization after filtered and buffy coat-depleted blood transfusion in cardiac surgery: a randomized...

WBC reduction of all blood components is being introduced in many countries. Prevention of immunologic side effects of transfusions is part of the motivation. To compare the immunogenicity of before- or after-storage WBC-reduced RBCs with RBCs without buffy coat, a randomized clinical trial was performed.

Cardiac surgery patients were randomly assigned to receive either RBCs without buffy coat (PCs), WBC-reduced RBCs that were filtered before storage (FFs), or WBC-reduced RBCs that were filtered after storage (SFs). Serum samples for antibody analyses were collected before and after surgery.

Sera of 404 patients were tested. Of the 317 patients with negative preoperative screening, 12.6 percent developed anti-WBC antibodies (PC, 14.5%; FF, 9.6%; SF, 13.3%). Of the 87 patients with preoperative anti-WBC antibodies, 28.7 percent showed a marked increase in panel reactivity (PC, 31.3%; FF, 29.0%; SF, 25.0%). ELISA showed the newly formed antibodies to be of IgG class and directed against HLA class I in more than 90 percent of the samples tested. Newly formed anti-RBC antibodies appeared in 5.3 percent (PC, 7.1%; FF, 3.4%; SF 5.4%). Alloimmunization against WBCs and RBCs was strongly correlated (p < 0.01). The differences in newly formed anti-WBC antibodies and anti-RBC antibodies between the trial arms did not show significance.

Buffy coat removal, and additional WBC reduction by filtration, either before or after storage, result in similar posttransfusion alloimmunization frequencies after a single transfusion event with multiple RBCs.