Molecular biological study of lymphocytic stem cell leukemia

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We analyzed the immunoassociated genes, specially T-cell receptor(TcR)delta chain gene, of sixteen patients with CD7+stem cell leukemia as lymphocytic stem cell leukemia, and of nine patients with sinonasal malignant lymphoma.In 1993, we reported that the DDJdelta rearrangement are frequently shown in the patients with CD7+ stem cell leukemia and occur more earlier stage than that of expression of cytoplasmic CD3epsilon in T-cell development. These findings indicate DDJdelta to be a marker of T-lineage stem cell, and suggest that TcRdelta gene rearrangement occur as following ; DD*DDJ*VDDJ.In 1994, we documented that five out of sixteen patients with CD7+ stem cell leukemia, showed the specific clinical, immunophenotypic and immunogenotypic characteristics. We reported this subgroup as T-precursor leukemia/lumphoma. The T-precursor leukemia/lymphoma has some characteristics as following ; 1) on phenotypic examination, the phenotypes of blast cells correspond to those of early T cells between prothymocyte stage I and II,2) on the clinical feature at diagnosis, without blast cells in peripheral blood, with thymoma (4/5 cases) and lymphoadenopaty (4/5 cases) ; these patients achieved complete remission (5/5) but had relapse (4/5) , indicating transformation to mixed type (4/4, T/B/M-2 cases, T/M-2 cases) , 3) on immunogenotypic examination, the presence of the common Ddelta2 (D) Jdelta1. The more intensive chemotherapy including the stem cell transplantation should be considered to alter the poor prognosis of T-precursor leukemia.In nine patients with sinonasal malignant lymphoma, which is generally considered to be T-cell lineage, 8 cases were suggested to be originated from Natural killer (NK) cell, which in many patients correspond to fetal NK cell type with cCD3. This finding suggests the presence of common precursor to both NK cell and T-cell. The lymphoma cells of all nine patients have the monoclonal integration of Epstein Barr virus.