Brucella abortus injected into CBA mice replicated primarily in the spleen and liver, reaching a peak bacterial count in both organs about 7 days postinfection. The organism was eliminated from the liver but declined to a chronic phase in the spleen. The infection caused hepatosplenomegaly. An influx of macrophages into the two organs was monitored by quantitative Northern (RNA blot) analysis o...

Three different methods of measuring the proliferative capacity of transplanted mouse bone marrow were used to study the effects of preirradiation of the recipient. Recipient mice were exposed to 700 R and given graded numbers of syngeneic bone marrow. 7 days were allowed for proliferation of these cells, and then the granulocytic or erythrocytic progeny was measured. The former was determined ...

The degree of redundancy between thrombopoietin (Tpo) and steel factor (SF) cytokine pathways in the regulation of hematopoiesis was investigated by generating mice lacking both c-Mpl and fully functional c-Kit receptors. Double mutant c-Mpl;Kit mice exhibited reduced viability, making up only 2% of the offspring from c-Mpl;Kit intercrosses. The thrombocytopenia and megakaryocytopenia character...

Transgenic female mice expressing the transforming rat oncogene c-erbB-2 (HER-2/neu) under the mouse mammary tumor virus (MMTV) promoter (BALB-neuT) spontaneously develop mammary carcinomas with a progression resembling that of human breast cancer. In these mice, activating antitumor immunotherapy fails to induce T cell-mediated cytotoxicity, suggesting a suppression of the immune response. We ...

The effects of acute thrombocytopenia, produced by platelet antiserum (PAS), on both megakaryocyte colony-forming cells (Meg-CFC) and granulocyte-macrophage colony-forming cells (GM-CFC) were studied. During the 1-hr to 14-day period following acute thrombocytopenia (platelet counts < 5% of normal), bone marrow and splenic cells of C57BL/6J mice were obtained and cultured for 7 days in 0.3% aga...

Hematopoietic reconstitution following syngeneic bone marrow transplantation with graded doses of untreated and drug-treated bone marrow was studied in B6D2F1 mice. Granulocyte-macrophage colony-forming units (CFU-GM) and spleen colony-forming units (CFU-S) showed similar in vitro drug sensitivities. Both the speed of hematologic recovery and survival of mice transplanted with untreated or drug...

The effect of melphalan on mouse myeloma and hemopoietic progenitor cells was studied with a primary cell culture assay for mouse myeloma stem cells developed by Park, Bergsagel, and McCulloch and bone marrow cell culture and spleen colony assays for hemopoietic progenitor cells. Myeloma and bone marrow cells were exposed in vivo to graded doses of melphalan and harvested 3 and 24 hr later for ...

Although severe hematologic and immunologic disorders occur in several viral infections, insight into the mechanisms by which viruses may affect hemopoietic tissues is poor. The previous demonstration of distinct immunohemopoietic lesions in mice with acute lymphocytic choriomeningitis (LCM) virus infection has led us to investigate the function of hemopoietic precursor cells in the course of t...

Bone marrow cell liquid cultures were incubated at various oxygen concentrations ranging from 0% to 18% (air). The total number of cells in culture (CT) at the end of a 6-day incubation was found to be directly proportional to the oxygen concentration. As compared with air-incubated controls, cells recovered from severely hypoxic (1% oxygen) day-5 liquid cultures showed (1) the same day-7 colon...

c-mpl, the cellular homologue of the v-mpl oncogene transduced in the myeloproliferative leukemia virus (MPLV), encodes the receptor for thrombopoietin, a cytokine involved in the proliferation and differentiation of cells of the megakaryocytic lineage. Here, we show that a retrovirus containing murine c-mpl cDNA (HSFmmpl) is pathogenic in vivo when inoculated in adult mice. All mice developed ...