Koichi Ikuta

The interaction of the mouse c-kit receptor, designated Kit receptor, and steel factor promotes the proliferation and differentiation of hematopoietic progenitor cells. Monoclonal antibodies against the extracellular portion of the mouse Kit receptor were established. Five percent to 10% of total bone marrow cells expressed the Kit receptor, and half of them lack the expression of lineage markers. The Kit receptor was expressed on 70-80% of Thy-1.1lo Lin-Sca-1+ cells, which express Thy-1.1 antig

We have purified the human lymphocyte Fc receptor specific for IgE (Fc epsilon receptor) and its soluble form by using the anti-Fc epsilon receptor monoclonal antibody H107. Using an oligonucleotide probe corresponding to the partial amino acid sequence of the soluble Fc epsilon receptor related to IgE binding factor, we cloned, sequenced, and expressed a cDNA for the receptor. The Fc epsilon receptor has 321 amino acid residues with no NH2-terminal signal sequence. The receptor was separated in

Highly enriched pluripotent and multipotent hematopoietic stem cells (HSCs) are isolated from bone marrow and fetal liver as Thy-1loLin-Sca-1+ cells. Pluripotent HSCs express c-kit receptor on their surface, but the generation and proliferation of early fetal HSCs take place in the absence of steel factor. T precursor cells migrate into the fetal thymus by chemotactic mechanism. CD4lo precursors represent a newly defined phase of T-cell development in the thymus between the bone marrow-derived s

IL-7 is a cytokine crucial for development and maintenance of lymphocytes and other hematopoietic cells. However, how IL-7-expressing cells are distributed in lymphoid organs is not well known. To address this question, we established and analyzed IL-7-GFP knock-in mice. Thymic epithelial cells (TECs) expressed high GFP levels in the cortex and medulla, as detected with an anti-GFP Ab. Thymic mesenchymal cells also expressed GFP. Flow cytometry analysis suggested that cortical TECs expressed hig

We have cloned three pairs of rearranged and germ-line variable region (V beta) genes of the beta chain of the human T-cell receptor from the cell lines ATL2, ATL12, and MT-1 of patients with adult T-cell leukemia (ATL). The pairs were derived from the same (for ATL2 and ATL12) and different (for MT-1) individuals. Comparison of the nucleotide sequences showed no somatic mutation in V beta X ATL2 and beta X ATL12-2. Although one nucleotide change was found in V beta X MT1-1, the possibility of p