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T Kaisho

Publications and source records attributed to T Kaisho.

40 records · Page 3Linked to original sources
PubMed1992

A stromal cell-specific monoclonal antibody augments the stromal cell-dependent B lymphopoiesis.

We produced the mAb R25 against the stromal cell line ST2, which could support B lymphopoiesis in vitro. R25 enhanced the ability of ST2 to support B lymphopoiesis and precipitated molecules of 110 and 120 kDa (p110/120) from ST2 cell lysates. p110/120 were also expressed on other stromal and fibroblast cell lines but not on freshly isolated bone marrow hematopoietic cells, spleen cells, and lymphoid cell lines. However, R25 had no or weak effect on the stromal cell-dependent myelopoiesis. Even under conditions in which bone marrow cells were separated from stromal cells with a membrane filter, R25 could augment the stromal cell-dependent B lymphopoiesis. However, R25 did not induce the increase of IL-7 mRNA of ST2 cells. Taken together, these findings suggest that the stromal cell surface molecules p110/120 are involved in the stromal cell-dependent B lymphopoiesis and that certain soluble factors distinct from IL-7 may contribute to the p110/120-mediated B cell generation.

Animals↗
PubMed1990

Identification of the intracytoplasmic region essential for signal transduction through a B cell activation molecule, CD40.

CD40 is a 45-kDa glycoprotein expressed on human B lineage cells. Anti-CD40 induces the proliferation of B cells and the extracellular region of CD40 is related to those of a certain kind of growth factor receptors. Therefore, it has been proposed that CD40 might be a receptor for a molecule involved in the growth regulation of B cells. The cDNA coding for CD40 was transfected into the murine B lymphoma cell line M12 and the murine thymoma cell line EL4. The growth of both M12 and EL4 transfectants expressing human CD40 was inhibited by anti-CD40. Phorbol 12-myristate 13-acetate (PMA) augmented the growth inhibitory effects of anti-CD40 on transfectants. The CD40 molecule was constitutively phosphorylated not only in human tonsil B cells but also in transfectants expressing CD40. PMA augmented the phosphorylation of CD40 in these cells. These results indicate that in spite of the growth inhibitory effect of anti-CD40, the augmentative effect of PMA is conserved in CD40+ transfectants and suggest that the transfectant might be useful for the study of signal transduction mechanism through CD40. To investigate which part of the CD40 molecule is important for signal transduction, transfectants expressing mutant CD40 cDNA were established and their growth response to anti-CD40 was evaluated. The mutant molecule, which had an Ala for Thr substitution at position 234, and the deletion mutants lacking Thr234 were inactive in growth signal transduction, indicating that Thr234 itself or the region around Thr234 is essential for signal transduction through CD40.

Animals↗
PubMed1986

Molecular structure of human lymphocyte receptor for immunoglobulin E.

We have isolated and sequenced a cDNA clone encoding the human lymphocyte receptor for IgE (Fc epsilon R). The deduced protein sequence reveals that Fc epsilon R consists of 321 amino acids, without any signal sequence, and is oriented with its N-terminus on the cytoplasmic side and its C-terminus on the outside of the cell. This molecule shows striking sequence homology with chicken asialoglycoprotein receptor (hepatic lectin), suggesting a possible role for Fc epsilon R in endocytosis. Fc epsilon R mRNA is expressed in B cells, B cell lines, and macrophage cell lines. It is not expressed in T cells or T cell lines, with the exception of an HTLV-transformed T cell line. mRNAs expressed in a macrophage line and in the latter T cell line differ in size from mRNA expressed in B cells. Human BSF-1 (or IL-4) induces the expression of Fc epsilon R mRNA in B cells, but not in T cells.

Amino Acid Sequence↗