Erythrocyte autoantibodies and expression of CD59 on the surface of red blood cells of polytransfused patients with ß-thalassaemia major

Abstract

Repeated transfusions for the treatment of thalassaemia major cause an insult to the patient's immune system and provoke post-transfusion purpura and haemolytic reactions that can be severe and life threatening. This study aims to investigate the presence of erythrocyte autoantibodies and CD59 expression on the surface of red blood cells (RBCs) in patients with beta-thalassaemia major, and any relationship to frequency of blood transfusion. The study looks at a total of 49 patients (both children and adults) with beta-thalassaemia major, divided into four groups according to the number of blood transfusions received and the presence or absence of the spleen. Glycosylated haemoglobin, Coombs' test (direct and indirect) and CD59 level on the RBC surface (by flow cytometry) are estimated in all patients studied. Glycosylated haemoglobin level was significantly lower in those who had received less than 10 units of blood (group III) than in those who had received more than 25 units of blood and had undergone splenectomy (group Ib), and was significantly lower in those who had received 10-25 units of blood (group II) than in those that comprised group Ib (F=3.598, P=0.0205). Considering CD59 expression, there was a marked difference between the groups. Expression was highest in group III and diminished progressively through groups II, Ia (polytransfused, non-splenectomised) and Ib (F=19.83, P=0.0000). No relationship was observed between CD59 expression and either blood group or gender. A significant negative correlation between CD59 expression and reticulocyte percentage (r=-0.538, P=0.000) and normoblast count (r=-0.5455, P=0.000) was found. A negative correlation between lymphocytosis and CD59 expression was also noted in groups III (r=-0.745, P=0.013), Ia (r=-0.5849, P=0.022) and Ib (r=-0.6711, P=0.009). Direct Coombs' test was positive in only one patient in group Ib, who also showed the lowest haemoglobin level. Thalassaemia patients exposed to multiple antigens through repeated blood transfusions showed lower CD59 expression than did those who had received fewer transfused units, which is a good method of detecting potential autoantibodies. Furthermore, a negative Coombs' test does not exclude autoimmunisation in such patients.

The James Blundell Award Lecture 2007: Do we really understand immune red cell destruction?

“…Unlike PNH, the quantity of CD55 and CD59 on sickle cells is normal; Test & Woolworth (1994) suggested that there may be a functional defect of CD59. It is of interest to note that some patients with thalassaemia suffer from ‘hyperhaemolysis’ (Sirchia et al , 1997) and their RBCs have also been shown to have similar findings concerning CD59 and cytolytic C5b‐9 (Malasit et al , 1997; Salama et al , 2004). Hyperhaemolysis has also been observed in some patients with chronic diseases other than heamoglobinopathies (Treleaven & Win 2004; Darabi & Dzik, 2005) but CD55/59 were not studied in these reports.…”

Prevalence of Alloimmunization against RBC Antigens in Thalassemia Major Patients in South East Of Iran

“…Alloimmunization against red blood will increase the need for blood transfusions in patients with thalassemia. Some alloantibodies are hemolytic and may cause hemolytic transfusion reactions and limit the availability of further safe transfusion but others are clinically insignificant [5,6].…”

The prevalence, alloimmunization risk factors, antigenic exposure, and evaluation of antigen‐matched red blood cells for thalassemia transfusions: a 10‐year experience at a tertiary care hospital

“…Furthermore, the risks of alloimmunization against transfused RBC alloantigens are complex and also depend on the recipient's immune status and the immune modulatory effect of the transfused RBCs on the recipient . Other risk factors reported are the age at initial transfusion, the number of units transfused, age, sex, genetic background, and environmental factors …”