الفهرس 
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Abstract
Beta thalassemia is a hereditary disorder characterized by a genetic deficiency in the synthesis of beta globin chains. It is inherited in an autosomal recessive pattern. It presents worldwide but more frequent in people of Mediterranean origin. In Egypt the prevalence is quite common. β-thalassemia characterized by abnormalities in the synthesis of the beta chain of hemoglobin resulting in variable phenotypes ranging from severe anemia to clinically asymptomatic individual. Clinically, the thalassemia is classified according to the severity into major, intermediate and minor forms. Thalassemia major is sever, transfusion dependent disorder it is also called Cooley’s anemia, while thalassemia intermedia is characterized by anemia and splenomegaly, though not of much severity as to regular transfusion. Thalassemia minor is symptomless carrier state.
Thalassemia major patients is suspected to be an infant with sever microcytic anemia and mild jaundice. Hepatosplenomegaly occurs as a result of excessive destruction, extra medullary hematopoiesis and later because of iron overload. Splenomegaly is associated with increased red cell destruction. Expansion of bones caused by intense marrow hyperplasia leads to thinning of cortex of many bones with tendency to fracture and bossing of the skull and Thalassemia faces. CBC of βThalassemia is characterized by microcytic hypochromic.RBCs show morphological changes as microcytosis, hypochromia, anisocytosis and poikilocytosis. Nucleated RBCs (Normoblasts) are detected in blood film related to the degree of anemia and markedly increase after splenectomy. Hemoglobin analysis is needed to confirm the diagnosis by electrophoretic or chromatographic techniques. This will usually show an increased amount of HbA2 with the vast majority of the remainder consisting of HbF and small amounts of HbA1 may be present depending on the β globin mutation.
Treatment of beta thalassemia depends on the severity of the disease and mainly depends on blood transfusion and iron chelating therapy. The decision to proceed to splenectomy is taken if the annual transfusion requirements rise above 200ml/kg/yr.
T regulatory cells (Tregs) are central for the maintaince of immune homeostasis and they can prevent transfusion reaction. Immunoregulation mediated by Tregs is critical for tolerance induction to transfused blood antigens. In vitro and in vivo experimental models have demonstrated that production of Tregs in the periphery from naïve T cell can lead to tolerance induction and decrease transfusion reaction. Repeated blood transfusions in patients with β-thalassemia cause multiple antigenic stimuli that might change the Treg cells percentage.
The aim of work was to study the expression of CD4, CD25 in transfusion dependent beta thalassemia patient. We also discussed the role of CD4+CD25+ cells in febrile reaction to blood transfusion.
This study included 80 individuals we divided them into 3 groups: group I: 35 thalassemia major children, group II: 25 thalassemia intermediate children and group III: 20 age and sex matched healthy children from general population as a control group.
Full history was taken from parents of all children. All subjects of the study had complete clinical examination and investigations. The investigations included CBC and CD4 and CD25 expression by flowcytomerty.
The results of the current study showed that, the difference between group I and group II was not statistical significant regarding CD4+CD25+ and CD4+CD25bright expression. Also, between group II and group III. But, there was statistical significant difference between group I and group III. Also, there was overall statistical significant difference between the three groups.
Regarding febrile reaction to blood transfusion, there was statistical significant relation between CD4+CD25+ expression and febrile reaction in group I and group II. The mean was lowest among those who had always febrile reaction to blood transfusion, followed by those who sometimes developed febrile reaction, followed by who rarely developed febrile reaction and the highest was in those who never developed febrile reaction to transfusion.
There was no statistically significant relation between CD4+CD25bright expression and febrile reaction in group I, but there was statistically significant relation in group II. The lowest CD4+CD25bright expression was in those who had always febrile reaction to blood transfusion, higher in those had sometimes febrile reaction, higher in those who had rare reaction, and the highest was in those who never had febrile reaction to blood transfusion.
from the results of our study we concluded that, there was no statistical difference in CD4+CD25+ and CD4+CD25bright cells between thalassemia major and thalassemia intermediate but the difference was significant between thalassemia major group and healthy control. There was statistical relation between CD4+CD25+, CD4+CD25bright cells and febrile reaction to blood transfusion. The higher the level of CD4+CD25+ and CD4+CD25bright, the less is the frequency and magnitude of febrile reaction. So, CD4+CD25+ and CD4+CD25bright expression has inverse relationship with the frequency and magnitude of non-hemolytic transfusional febrile reaction.