The important number of blood units, transfused in major thalassaemia, leads to increasing risk of immune reactions, due to antibodies developed against different antigens on platelets, leukocytes, red blood cells, proteins.

The present study tries to establish as scale of the immune posttransfusional response in 95 patients with major thalassaemia, registered in Romania during the last 10 years. Upon the degree of transfusional needs, for accurate results, 3 categories of patients were established: I=1 to 10 transfusions per year, II=11 to 20 transfusions per year and, respectively, III= more than 20 transfusion per year. The number of patients in each category became a variable figure, following the age and the individual evolution of the disease. The transfusional therapy was initiated with whole blood, then with RBC concentrate and intermittent Desferrioxamine administration. During the last year, the constant treatment with iron chelators became possible.

Blood grouping, phenotyping (Rh-Kell) and compatibility testing of the units to be transfused were done (standard methodology) for every patient.

The immediate incidents were registered and proved to be: allergic reactions 62% and immune reactions 27,2% - mostly anti-leukocyte and anti-platelets antibodies: 21,3%. The relatively low frequency of irregular antibodies against erythrocytes antigens - 6,9% could be explained by the transfusion of selected blood units, but also by an increased frequency of a certain Rh phenotype in the disease. Taking into account that Rh antigens have the highest immunogenic potential, the presence of a complete constellation of the system (59,25% for DCcEe), could be a natural protection of the thalassaemic individual, genetically induced.

A relation between a certain ABO blood group frequency and the disease could not be established, the results being similar with the structure to be found in healthy population.