WBC reduction of RBC transfusions is associated with a decreased incidence of RBC alloimmunization.
BACKGROUND
Allogeneic transfusion stimulates Th2 (humoral) immunity. A hypothesis was developed that WBC reduction, by reducing the Th2 stimulus associated with transfusions, might reduce RBC alloimmunization.


METHODS
The first retrospective cohort study involved determining the prevalence of newly detected alloimmunization in transfused patients with acute myeloid leukemia (AML) in our hospital in the period before WBC reduction and after its introduction for this particular group of patients. The second study involved determining the incidence of newly detected RBC alloimmunization in all transfused hospital patients during three annual periods with WBC-reduction prevalences ranging from 0 to 100 percent.


RESULTS
The alloimmunization prevalence rate in AML patients was 8.2 percent in those receiving non-WBC-reduced RBCs and platelets (n=195) and 2.8 percent in those receiving only WBC-reduced components (n=215) (p=0.016). In all patients, the alloimmunization incidence rate decreased from 3.47 per 1000 antibody screens in 1987 (no WBC reduction) to 2.97 per 1000 in 1999 (40% of transfusions WBC-reduced) to 2.38 per 1000 in 2001 (100% of transfusions WBC-reduced) (p=0.0298). A decrease in alloimmunization was observed in both males and females, with the decrease more clearly evident in males.


CONCLUSIONS
These preliminary data support the hypothesis that WBC reduction may be associated with a reduced frequency of RBC alloimmunization. These findings require confirmation and further investigation.
Blumberg
Neil
N
Department of Pathology and Laboratory Medicine, University of Rochester Medical Center and Strong Memorial Hospital, Rochester, New York 14642, USA. Neil_Blumberg@urmc.rochester.edu
Heal
Joanna M
JM
Gettings
Kelly F
KF
D001781:Blood Component Removal; D001789:Blood Group Antigens / Q000276:immunology; D001787:Blood Group Incompatibility / Q000453:epidemiology* / Q000276:immunology; D015331:Cohort Studies; D017707:Erythrocyte Transfusion; D005260:Female; D006801:Humans; D007518:Isoantibodies / Q000097:blood; D015470:Leukemia, Myeloid, Acute / Q000276:immunology / Q000628:therapy; D007962:Leukocytes / Q000276:immunology; D008297:Male; D011247:Pregnancy; D012189:Retrospective Studies; D012204:Rh-Hr Blood-Group System / Q000276:immunology; D012727:Sex Characteristics; D018418:Th2 Cells / Q000276:immunology
D001789:Blood Group Antigens; D007518:Isoantibodies; D012204:Rh-Hr Blood-Group System