Impact of azacitidine on red blood cell alloimmunisation in myelodysplastic syndrome.

Background. The incidence of alloimmunisation in myelodysplastic syndromes (MDS) during the era of supportive treatment ranges from 9 to 56%. However, it is unknown if the widespread use of hypomethylating agents has changed the risk of immunisation. The aim of this study is to evaluate the impact of azacitidine (AZA) therapy on red blood cell (RBC) alloimmunisation in transfused patients with MDS, myelodysplastic syndromes/myeloproliferative syndromes (MDS/MPS) and secondary acute myeloid leukaemia (AML). Material and methods. We have analysed retrospectively all patients with MDS, MDS/MPS and secondary AML from MDS, who received their first transfusion in our hospital between January 1995 and December 2014. We have assessed the impact of age, sex, RBC and platelets units transfused, and AZA treatment on developing alloantibodies. Results. In our study, the number of RBC units transfused increased the risk of developing alloantibodies. However aging and the treatment with AZA were associated with a lower rate of alloimmunisation. Discussion. Patients with MDS, MDS/MPS and secondary AML who received treatment with AZA developed RBC antibodies at a lower rate than control group. We suggest that aging and immunosuppression due to AZA therapy could develop an immunological tolerance with a weak response to allotransfusions.