Background: Approximately 80% of patients with myelodysplastic syndromes (MDS) receive multiple red blood cells (RBC), often multiple transfusions, and are therefore prone to develop alloantibodies against RBC. Because of increasing evidence for the role of immune dysregulation in the pathobiology of MDS, we hypothesized that in patients with MDS there is an increase in alloantibody formation beyond that expected by multiple transfusions.

Objectives: To determine the prevalence rates of alloantibodies in patients with MDS who are transfusion dependent and compare them to those of non-MDS patients matched for number of RBC units they received. 

Methods: The blood bank database was screened to identify non-MDS patients matched for age and number of units transfused. Logistic regression analysis was applied to determine factors affecting alloantibody formation. 

Results: Of 60 patients with MDS, 18 (30%) developed alloantibodies against RBC. Transfusion-dependent MDS and non-MDS patients (N=56 each), matched for number of RBC units and age, were compared. Fifteen MDS patients (27%) but only 12 non-MDS patients (12%) developed alloantibodies (P = 0.057). The relative risk for developing antibodies in MDS patients was 2.14, and MDS was the strongest predictor for formation of alloantibodies during transfusion therapy (odds ratio 3.66, confidence interval 1.4–9.3). 

Conclusions: Patients with MDS are at increased risk to develop RBC alloantibodies, partly because these patients receive multiple RBC transfusions. Whether matching for RH and KEL would lead to lower rates of RBC alloantibodies remains to be determined.