Red cell immunization in beta thalassaemia major

To find out the frequency, pattern and factors influencing red cell immunization secondary to multiple blood transfusions in patients of beta-thalassaemia major.

A cross-sectional study.

Armed Forces Institute of Transfusion, Rawalpindi, in November 2002.

One hundred and sixty-one patients suffering from beta-thalassaemia major and on regular blood transfusions were included in the study. Their blood samples were tested for blood grouping, direct antiglobulin test and antibody screening/identification using reagents of DiaMed-ID Gel microtyping system.

The total rate of red cell immunization was found to be 6.84%. Red cell alloantibodies were detected in 4.97% patients, and belonged mainly to Rh system, with one example each of anti-K, anti-Jsb and anti-Jka. Direct antiglobulin test was positive in 3 patients (1.87%) with increased hemolysis. Two had warm panreactive IgG antibodies suggesting red cell autoimmunization. Red cells of the 3rd patient showed sensitization with c-3d, with presence of an autoreactive cold agglutinin in the serum having a titre of 1:4. The red cell alloantibody formation was not influenced by age at first transfusion, number of blood transfusions and ethnicity.

The rate of red cell alloimmunization in beta-thalassaemia major is relatively low in our setup and may be related to red cell homogeneity between the donor and recipient population. Routine pre-transfusion matching of blood, other than ABO and Rh "D" antigens is not recommended because of low rate of red cell alloimmunization, and high costs associated with such testing. Hyperhaemolysis, due to acquired red cell autoantibodies was found to be an important complication. Patients who develop this complication should be tested for presence of underlying alloantibodies and considered for immunosuppressive treatment.