Decreased expression of transcription factor GATA-2 in haematopoietic stemcells in patients with aplastic anaemia

Aplastic anaemia is characterized by reduced haematopoiesis resulting in pa ncytopenia. It has been speculated that there is an injury in haematopoieti c stem cells in the bone marrow: however, the precise nature of the injury has not been elucidated. In this study, the levels of expression of mRNAs f or three transcription factors, GATA-2, SCL and AML1, which function in the early stages of haematopoiesis, were examined by quantitative polymerase c hain reaction in patients with aplastic anaemia, idiopathic thrombocytopeni c purpura (ITP) and normal subjects. Among these factors, expression of GAT A-2 mRNA in purified CD34-positive cells was markedly decreased in aplastic anaemia compared with that in ITP and in normal subjects. The expression l evels of SCL and AML1 mRNA in CD34-positive cells in aplastic anaemia were not different from those in normal subjects. When the expression of GATA-2 protein in CD34-positive cells was examined by immunocytochemical analysis, the percentage of GATA-2-positive cells in aplastic anaemia was lower than that in normal subjects. These findings strongly suggest that there is an aberrant expression of transcription factors in stem cells in aplastic anae mia. which may be responsible for the development of the disease.