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The efficacy of recombinant human interferon alpha-2b (rh IFN alpha-2b) in the treatment of steroid resistant idiopathic thrombocytopenic purpura (ITP) was studied in 50 cases. Forty-one patients treated with rh IFN alpha-2b three times a week, six of 18 (33.3%) in the low dose group (150 x 10(4)IU: 3 MIU) and four of 20 (20.0%) in the high dose group (300 x 10(4)IU: 3 MIU) responded with platelet counts increasing to above 50 x 10(9)/L. Because of the exacerbation of thrombocytopenia and nasal bleeding, treatment was discontinued within 2 weeks in three patients out of 41 cases. On the other hand, six of nine patients (66.7%) treated with 3 MIU of IFN alpha-2b once a week for 8 weeks showed satisfactory response. Treatment with either administration schedule did not result in sustaining platelet counts above 50 x 10(9)/L for a long time after treatment. The results indicate that once a week administration schedule of rh IFN alpha-2b is more efficacious for platelet counts increasing for short period in patients who failed to respond to steroid and other medications than other schedules. The maintenance of this treatment schedule will allow sustained increased platelet levels, resulting in relief of bleeding tendency, while also being cost effective in comparison with other IFN treatment schedules and achieving better patient compliance without flu-like symptoms.

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 μ-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 μ-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 μ 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 examing 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. © 1994 Wiley-Liss, Inc.

We report an 8-year-old boy with Ph-positive chronic myelogenous leukemia (CML) who showed a testicular tumor as the first manifestation of blastic crisis. Pathological examination of the excised testis revealed marked infiltration of immature cells, whereas bone marrow remained in the chronic phase. Immunohistochemical and molecular examinations disclosed the immature cells to have B-lymphocyte surface determinants and immunoglobulin JH rearrangement. DNA obtained from the testis and peripheral blood cells showed similarly rearranged bcr configurations, indicating that infiltrating cells in the testis originated from the CML clone. Bone marrow showed B-lymphoid blastic crisis 4 months after testicular involvement.