T-cell transcription factor GATA-3 is an immunophenotypic marker of acute leukemias with T-cell differentiation.

T-cell transcription factor GATA-3, known to play a role in early T-cell development and in the development of T-cell neoplasms, is expressed at high levels in fetal and adult thymus, as well as in acute leukemias with T-cell differentiation, including T-lymphoblastic leukemia/lymphoma (22/22 cases), early T-cell precursor lymphoblastic leukemia (11/11 cases), and mixed-phenotype acute leukemia, T/myeloid (4/5 cases), but only rarely in acute myeloid leukemia/myeloid sarcoma (1/36 cases), and not in B-lymphoblastic leukemia (0/16 cases). In contrast, T-bet, the other T-cell transcription factor that controls Th1/Th2 T-cell fate, is not expressed to any significant extent in immature thymocytes or in cases of T-lymphoblastic leukemia or acute myeloid leukemia/myeloid sarcoma, but is expressed in most cases (15/16) of B-lymphoblastic leukemia and in mixed-phenotype acute leukemia, B/myeloid. GATA-3-positive acute leukemias with T-cell differentiation were also found to express proto-oncogene C-MYC, in an average of 52% of neoplastic cells, which, along with GATA-3, may contribute to leukemogenesis, as suggested by transgenic mouse models. We conclude that GATA-3 is a sensitive and specific marker for the diagnosis of acute leukemias with T-cell differentiation and may be a useful addition to the panel of immunophenotypic markers for the diagnostic evaluation of acute leukemias.