Expression of Immune Checkpoints LAG-3, CTLA-4, TIM-3, and PD-1 in Beta-Thalassemia Patients Treated Using HbF...

Beta-thalassemia is an inherited hemoglobin disorder caused by mutations in the HBB gene encoding beta-globin chains. Severe anemia secondary to defective globin chains, chronic hemolysis, and ineffective erythropoiesis necessitate transfusion support from early childhood. Recently used treatment options with promising results in resource-limited countries include drugs that augment fetal hemoglobin (HbF), such as hydroxyurea and thalidomide. Although effective in alleviating anemia and related symptoms, these drugs, and particularly thalidomide, are also known for their immunomodulatory roles. Furthermore, repeated transfusions for patients with compromised immune systems increase the risk of infections and weakened immunity. The key regulators of immune systems include immune checkpoints, or cell surface molecules on immune cells. Limited studies are available on the expression of immune checkpoint molecules such as LAG-3, CTLA-4, TIM-3, and PD-1 in thalassemia and its treatment. This study aimed to compare LAG-3, CTLA-4, TIM-3, and PD-1 expression levels in patients treated using HbF-augmenting drugs or transfusions and with iron overload. The findings provide insight into immune regulation in beta-thalassemia and response to treatment.

Gene expression levels of LAG-3, CTLA-4, TIM-3, and PD-1 were quantified using real-time polymerase chain reaction in patients being managed with blood transfusions (n=33) or HbF-augmenting drugs (n=140) compared to healthy controls (n=27).

This study revealed increased expression of LAG-3 in patients regardless of treatment, whereas increased CTLA-4 was observed in patients receiving regular transfusions. The expression levels of TIM-3 and PD-1 were higher in patients receiving HbF augmentation therapy compared to both patients receiving blood transfusions and the healthy control group. A very weak to nonexistent correlation was found between serum ferritin and immune checkpoints.

The findings of this study are suggestive of alterations in immune regulation in beta-thalassemia that could be attributed to thalassemia itself, repeated exposure to blood products, recurrent infections, and the use of immunomodulatory drugs.