WBC reduction in RBC concentrates by prestorage filtration: multicenter experience

BACKGROUND: As universal leukocyte (WBC) reduction (ULR) is being considere d as a new standard, few data are available on the performance of WBC-reduc tion filtration in routine practice. The performance of WBC-reduction in RB Cs, using varied filtration practices, in meeting the current FDA requireme nt (<5 x 10(6)), Council of Europe (EC) recommendation, the proposed FDA re quirement (<1 x 10(6)), and a more stringent proposal (<5 x 10(6)) for resi dual WBCs per RBC unit was assessed and compared. STUDY DESIGN AND METHODS: Participating facilities were the 11 sites of the Viral Activation Transfusion Study (VATS), a prospective study of the impa ct of transfusion with and without WBC-reduction on survival and HIV viral load in HIV-1-infected patients. Patients randomly assigned to undergo WBC reduction were required to receive RBCs less than or equal to 14 days old t hat had undergone prestorage (within 72 hours of collection) WBC-reduction filtration by a method devised to achieve a postfiltration WBC count of <5 x 10(6). Residual WBC quantitation was performed by PCR in the central VATS laboratory by using frozen WBC-reduced RBC samples obtained at issue for t ransfusion. RESULTS: A total of 1869 WBC-reduced RBC units were studied. Filtration pra ctices varied within and between sites. There were significant differences in mean residual WBC counts at the 11 sites (p <0.001). Among the WBC-reduc ed RBC units, 0.8 percent exceeded <5 x 10(6) WBCs per unit, 8.3 percent ex ceeded 1 x 10(6), WBCs per unit, and 14.3 percent exceeded 5 x 10(5) WBCs p er unit. CONCLUSION: Residual WBCs in WBC-reduced RBC units vary within and between sites. WBC reduction was successful, in that over 99 percent and 91 percent of VATS WBC-reduced RBC units met US and EC thresholds, respectively. Howe ver, the small but measurable failure rate indicates that not every unit wi ll meet these guidelines.