[Immunohematologic study and transfusion approach to patients with public antibodies]

Abstract

Objectives: To analyze the different immunohematologic studies required to identify anti-red cell antibodies directed against high incidence antigens and comment the best tranfusion management.

Patients and methods: Five patients with suspected anti-red cell alloantibodies directed against high frequency antigens are reported. After a positive antibody screening test (AST), an agglutination test with a commercial panel of 24 red cells was performed. Red cells were treated with proteolytic enzymes and AET to try to identify the circulating antibody. However, it was necessary to send the samples to reference laboratories for definitive identification. In order to evaluate the haemolytic potential of the antibody serum samples were treated with DTT and immunoglobulin subtype was studied with the capillary agglutination test. Finally, we analyze the half life of Cr51 labelled red cells. To obtain compatible blood for transfusion, autologous transfusion and cross-match with blood from direct relatives were performed.

Results: AST was positive in every case. A decrease in the agglutination test was observed after ficin treatment in two patients, and an increase in the remaining. The treatment of red cells with ZZAP and AET resulted in a decrease of agglutination in three cases and an increase in the remaining two. Specificity of the antibodies was as follows: anti-Cellano (two cases), anti-Ku (one case) and anti-Yta (two cases). Anti-Kell antibodies were IgG1 and anti-Cartwright antibodies were IgG4. One patient was transfused with autologous blood alone, another patient received compatible blood from direct relatives. A third patient was transfused both with autologous and allogeneic compatible blood. The fourth patient did not need red cell transfusion and, finally the last patient had to be transfused with incompatible blood but no postransfusion haemolysis was observed.

Conclusions: In patients with anti-red cell antibodies against high-frequency antigens, red blood cells treatment with proteolytic enzymes (ZZAP, ficin) and AET are useful techniques to approach to their identification. Beside this, the study of type and subtype of Ig are necessary to know the haemolytic activity of the antibody. Regarding the transfusional management, autologous transfusion, crossmatch with blood from direct relatives and cryopreservation of compatible blood are the most adequate attitudes to cover future needs.