BACKGROUND.Recently, it was demonstrated that the human fetal thymocyte con-

A 63-year-old man presented with a perforation of the small intestine. A diagnosis of intestinal T-cell lymphoma (ITCL) was made from CD (cluster differentiation) 3 positivity and a rearrangement of T-cell receptor genes. The tumor also expressed CD56,which suggests it belongs to a rare subtype derived from activated cytotoxic intraepithelial T lymphocytes. Although the prognosis of ITCL has been considered to be very poor irrespective of CD56positivity, complete remission was achieved in this case by high dose chemotherapy followed by autologous peripheral blood stem cell transplantation (auto-PBSCT) even after relapse.Auto-PBSCT in the earlier stage of the disease might improve the prognosis. (Internal Medicine 41 : 734-737, 2002)

We established two cell lines, YN-1 and Y-1K, from the peripheral blood of two chronic myelogenous leukaemia patients in blastic crisis. Characterization of the YN-1 and Y-1K cells revealed that these cells expressed erythroid lineage markers. However, there was a marked difference in the level of gamma-globin mRNA and haemoglobin in YN-1 and Y-1K cells. YN-1 contained approximately 1-5% benzidine-positive staining cells, whereas no benzidine-positive cells were observed in Y-1K cells. Haemoglobin production in YN-1 cells was markedly increased with various chemical inducers of erythroid differentiation, but was not in Y-1K cells. In contrast, Y-1K cells expressed CD34 stem cell antigen and CD41 megakaryocyte-specific antigen. These observations suggested that, although both cell lines were committed to the erythroid lineage, each cell line represented a distinct differentiation stage in the erythroid differentiation programme. Y-1K seemed to correspond to an early stage of cells in erythroid lineage, whereas YN-1 represented a more advanced stage in human erythropoiesis.