Fusanari Horiuchi

Inhibition of growth and induction of apoptosis by all‐trans retinoic acid in lymphoid cell lines transfected with the PML/RARα fusion gene

The interaction of an exogenous PML/RARα fusion gene associated with acute promyelocytic leukaemia, with all‐trans retinoic acid (ATRA) was examined in two lymphoid cell lines. L1210 and MOLT‐4 cells were transfected with PML/RARα cDNA in the expression vector pGD and stable transformants (L1210PML/RARα and MOLT‐4PML/RARα) were selected with G418. ATRA inhibited the growth of these stable transformants, as assessed by [3H]thymidine incorporation, in a dose‐dependent manner, but had no effect on the growth of control cells stably transformed with neomycin resistant gene alone. ATRA also induced apoptosis, as assessed by fragmentation of genomic DNA, in L1210PML/RARα and MOLT‐4PML/RARα cells but not in control cells. The exogenous PML/RARα fusion gene therefore probably mediates the effects of ATRA on cell growth and apoptosis in these cell lines.

CD3 down‐regulating factor in sera and culture supernatants of leukaemic cells from patients with adult T cell leukaemia

Immunological abnormality of T lymphocytes in patients with adult T cell leukaemia (ATL) is characterized by abnormal expression of the 55 kD chain of the receptor for interleukin 2 (IL‐2R/p55) (Tac), and the down‐regulation of CD 3 expression. Using serum and culture supernatants of leukaemic cells from ATL patients (Group A) whose CD 3 expression was down‐regulated and those (Group B) whose CD 3 was not low, the possible mechanism of CD 3 down‐regulation on ATL cells was discussed. When PBMC from normal individuals were cultured with sera from ATL patients for 24 h, CD 3 expression revealed by mean fluorescent intensity (MFI) was down‐regulated by sera from ATL patients in Group A (MFI: Pt 1 = 51.6 ± 4.5, Pt 2 = 48.0 ± 6.9, control = 96.5 ± 6.6), not by sera from patients in Group B (MFI: Pt 3 = 105.5 ± 7.9, Pt 4 = 102.5 ± 8.3, control = 96.5 ± 6.6). When normal PBMC were cultured with supernatants of leukaemic cells from ATL patients in Group A, this CD 3 down‐regulating activity was also detected (MFI: Pt 1 = 78.0 ± 10.2, Pt 2 = 70.6 ± 8.7, control = 94.0 ± 6.6). By using gel‐chromatography, the fractionated supernatants from ATL patients in Group A decreased CD 3 expression of normal PBMC significantly (MFI: Pt 1 = 22.9 ± 5.8, Pt 2 = 28.8 ± 7.4, control = 92.1 ± 9.6). This CD 3 down‐regulating activity in fractionated supernatant was not inhibited by any lymphokine antibodies, anti‐IL‐1α antibody (Ab), anti‐IL‐1B Ab, anti‐IL‐2 Ab, anti‐IL‐3 Ab, anti‐IL‐4 Ab, anti‐IL‐6 Ab, anti‐TNF‐α Ab and anti‐IFN‐γ Ab. Any known cytokines (IL‐1, IL‐2, IL‐3, IL‐4, IL‐6, TNF‐α and IFN‐γ) could not modulate CD 3 expression of normal PBMC. These findings suggested that there are novel factor(s) with CD 3 down‐regulating activity in the serum and culture supernatant of ATL patient and those factor(s) are involved in progression of ATL.

Establishment of a myelodysplastic syndrome (MDS)/secondary AML-derived T lymphoid cell line K2-MDS

We have established a T lymphoid cell line, K2-MDS, from the peripheral blood mononuclear cells (PBMC) of a patient with acute myeloblastic leukemia (AML) transformed myelodysplastic syndrome (MDS). K2-MDS cells are positive for the expression of CD4, CD5, CD13, CD25, CD71, CD95, HLA-DR and cytoplasmic CD3. Southern blotting analysis shows T cell receptor (TCR) beta chain genes rearrangements, whereas immunoglobulin heavy chain (IgH) genes are not rearranged. Further, the patient PBMC contains TCR beta chain genes rearrangements in the same manner as K2-MDS cells. The data indicate that K2-MDS is a T lymphoid cell line derived from a myelodysplastic clone in the patient PBMC. This new MDS-derived cell line K2-MDS may be a useful in vitro model for studies on the pathogenetic mechanisms leading to MDS.

Elevated levels of soluble ICAM-1 in serum of patients with acute myeloid leukemia undergoing bone marrow transplantation

Serum soluble ICAM‐1 concentrations were measured in 10 patients with or without chronic graft‐vs.‐host disease (GVHD) after allogeneic bone marrow transplantation. The serum soluble ICAM‐1 levels in the patients with chronic GVHD were significantly higher than that in the patients without chronic GVHD. The data indicated that serum soluble ICAM‐1 is a useful parameter for predicting chronic GVHD.

Possible involvement of protein kinase C activation in down-regulation of CD3 antigen on adult T cell leukaemia cells

Summary The role of protein kinase C (PKC) system on CD3 expression on adult T‐cell leukaemia (ATL) was examined. The down‐regulation of CD3 on ATL cells is reportedly induced by CD3 down‐regulating factor (CD3DF) contained in serum and culture supernatants of leukaemia cells from acute type ATL patients. After we cultured normal PBMC with a PKC inhibitor, H‐7, CD3DF activity for PBMC was reduced significantly. Culture with H‐7 of HTLV‐1 transformed T cells, ATL‐2 cells whose CD3 expression had been decreased, led to enhancement of CD3 expression in a time‐dependent manner. These findings suggest that CD3DF may play an important role as a PKC system activator, resulting in CD3 down‐regulation.

Soluble intercellular adhesion molecule-1 levels of patients with acute myeloid leukemia after allogeneic bone marrow transplantation☆☆☆★

Concentrations of serum-soluble intercellular adhesion molecule-1 (ICAM-1) were measured for 10 patients with or without chronic graft versus host disease after allogeneic bone marrow transplantation. Levels of soluble ICAM-1 were higher among patients with chronic graft versus host disease than among those without it, a statistically significant difference. The results indicated that measurement of serum-soluble ICAM-1 is useful for prediction of chronic graft versus host disease.

Induction of anti-idiotypic T cells through a network mechanism

BALB/c mouse T cells that recognized the idiotype expressed on M104E(mu, lambda 1) were induced by immunization with Dextran B-1355. T cells derived from mice immunized with 1 mg of Dextran B-1355 showed a marked proliferative response against M104E, whereas T cells from mice immunized with Ficoll or smaller amounts of Dextran B-1355 did not. BCL1Id, which had an identical isotype, did not induce proliferation of T cells. The T cell proliferative response against the idiotype on M104E required macrophages as antigen-presenting cells. The proliferative response was inhibited when antigen-presenting cells were treated with NH4Cl or chloroquine, which are antigen-processing inhibitors. These results indicate that anti-idiotypic T cells which recognized processed idiotopes could be induced physiologically through a network mechanism.