A human pro-B cell line, named JKB-1, was established from the bone marrow of a 16-year-old girl with acute lymphoblastic leukemia (ALL) in relapse. The origin of the JKB-1 cell line was indicated by its chromosomal and immunologic similarity to the patient's fresh leukemic cells. This cell line has been growing for more than 14 months in suspension culture medium and had a doubling time of about 24 hours. JKB-1 expressed terminal deoxynucleotide transferase (TdT) and early antigens (HLA-DR, CD19, CD24) of B cells, with heavy chain gene rearrangement. However, it did not express late antigens (CD10, CD20, CD21, CD22, CD23) of B cells, light chain gene rearrangement, and cytoplasmic mu-chain. These results suggested that JKB-1 is at the stage of "pro-B" cell or early B-cell precursors. This cell line was induced to differentiate after 7 days of co-incubation with irradiated bone marrow stromal cells because of the expression of pre-B cell antigens (CD10, CD20), cytoplasmic mu-chain, light chain gene rearrangement, and disappearance of TdT, JKB-1 cells adhered to a preestablished bone marrow stromal cell layer with string-like processes under scanning electron microscope. When JKB-1 cells were separated from the stromal layer by a cyclopore membrane with 0.45 micron pore size, they did not differentiate. Bone marrow stromal cell conditioned medium could not induce differentiation either. Thus it was suspected that direct contact between JKB-1 cells and stromal cells was required for differentiation. In methylcellulose semisolid medium, the colony size and number of JKB-1 cells were increased by stem cell factor (SCF), or interleukin (IL)-3, or IL-7, but they were decreased by IL-6. Moreover, SCF synergized with IL-3 or IL-7 to stimulate the proliferation of JKB-1 cells. Because there are very few reproducible models for examining early stages of human B-cell differentiation, the JKB-1 cell line would be useful for studying the relationship between human B-cell differentiation and bone marrow microenvironment, as well as leukemogenesis.
This paper reports on a patient with lymphoma syndrome leukemia (LSL) who showed interesting findings on brain computed tomography (CT) and ultrasound scans of the abdomen at the initial presentation. The patient was a 5 year old girl. When she was admitted to our hospital, there were many lymph nodes palpable. The abdomen was distended and the liver and spleen were palpable below the umbilicus. Hematologic examinations revealed a leukocyte count of 275 800/μL with 98% lymphoblasts. Chest X‐ray film revealed a mediastinal mass. The diagnosis of LSL was made. Her brain CT scan showed a low density area in the right thalamic region without contrast enhancement; infarction was suspected. Furthermore, her abdominal ultrasound scan showed hepatosplenomegaly, kidney swelling with increasing echogenicity and hydronephrosis and stones in the renal pelvis and bladder. These findings are unprecedentedly rare in cases of childhood acute lymphoblastic leukemia (ALL), much less in LSL.
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