T Regulatory Cells Frequency During Maintenance Phase Chemotherapy for Pediatric Acute Lymphoblastic Leukemia

Abstract

<strong>Background:</strong> Drugs used in cancer treatment specifically kill T regulatory cells. <strong>Objective:</strong> To determine different phenotypes of T regulatory cells during the maintenance phase chemotherapy for pediatric acute lymphoblastic leukemia (ALL). <strong>Materials:</strong> We evaluated the percentages of regulatory T cells by flow cytometry. Soluble CTLA-4 (sCTLA-4) in plasma was evaluated by ELISA assay. <strong>Results:</strong> Increased percentages of CD4⁺CD25⁺ T cells, CD4⁺CD39⁺ T cells, CD4⁺Foxp3⁺ T cells, and CD4⁺CD25^High T cells were observed in children with ALL in comparison to healthy controls. In addition, the ALL patients with >12 months of therapy showed increased CD4⁺CD39⁺ T cells compared to the ALL patients with ≤12 months and healthy controls. Similarly, the CD4⁺CD25⁺ T cells and CD4⁺Foxp3⁺ T cells increased according to maintenance therapy time. <strong>Conclusion:</strong> Our results showed increased percentages of regulatory T cells in pediatric ALL patients despite chemotherapy, which might be compromising the anti-leukemic cellular immune response.