Regulatory T-cells in Acquired Aplastic Anaemia
Keywords:Anti-Thymocyte globulin, Aplastic anaemia, Flow cytometry, Regulatory T-lymphocytes, T-cells
Abstract: Introduction: Acquired aplastic anaemia is characterized by destruction of haematopoietic stem cells by cytotoxic T lymphocytes. Regulatory T-cells have been reported to be suppressed in aplastic anaemia like many other autoimmune disorders. Haematopoietic response and haematological recovery after successful immunosuppressive treatment provide the most powerful evidence for the immune mediated basis of this complex disorder. Objective: The aim of this study is to determine the deficiency of CD4+ CD25+ T regulatory cells prior to ATG induction/therapy in patients of aplastic anaemia. Methods: The patients were enrolled in a dose finding study for ATG-Fresenius (Fresnious Biotec, Gernmany). Aplastic anaemia was diagnosed as per standard guidelines. Bone marrow trephine biopsy was done to assess disease severity and for classification according to Camitta classification. Flow cytometry was done using four colour flow cytometer FACSCaliber. Results: The median age of the patients was 23 years (range 7-63 years). Out of 18 patients, there were 12 (66%) males and 6 (34%) females. Of the 18 evaluable patients, the number of patients with NSAA, SAA, and VSA was 10, 5, and 3 respectively. CD4+ and CD8+ T cells, and B cells in peripheral blood were calculated. The pre-treatment average Treg frequencies in NSAA was 16.5 ± 18.8, SAA 29.1 ± 18.3 and VSAA was 12 ± 11.7 respectively. The median time from diagnosis up to the last follow-up was 1.1 years (range: 0.1 3.0). Conclusion: The study concluded that Tregs were decreased in all patients of acquired aplastic anaemia, as in other autoimmune diseases.