Human myeloid precursors forming colonies in diffusion chambers expresses the Ia-like antigen

Normal human bone marrow contains cells capable of forming myeloid colonies (CFU-DG) in fibrin clots in diffusion chambers placed in the peritoneal cavity of cyclophosphamide-treated mice. Evidence has accumulated indicating that these colony-forming cells represent an earlier stem cell than the granulocyte-monocyte precursor cell (CFU-C) assayed in soft agar. We provide data showing that these stem cells express the "Ia-like" or DR antigen. In the presence of rabbit Ia antiserum at a titer of 1:300, all CFU-DG were inhibited. Cytotoxicity was complement-dependent. Data are also presented that suggest that the megakaryocyte stem cell also expresses the Ia antigen.

Growth of mouse and human bone marrow in diffusion chambers in mice. Development of myeloid and erythroid colonies and proliferation of myeloid stem cells in cyclophosphamide- and erythropoietin-treated mice

Both murine and human bone marrow cells were cultured in plasma clots which were formed inside diffusion chambers implanted into cyclophosphamide- and saline-treated mice. After an initial fall, the number of mouse bone marrow cells and numbers of mouse myeloid stem cells (CFU-C) and agar cluster-forming units rose faster in the cyclophosphamide-treated animals. These hosts also favored formation of myeloid (CFU-D-G) and erythroid (CFR-D-E) colonies and myeloid higher than those of CFU-C from the same marrow population. These observations suggest the existence of humoral factors stimulating granulocyte progenitor cell replication and differentiation. At its best the increment of CFU-D-E number was equivalent to that caused by a single 0.1 unit erythropoietin dose. Culture of normal human marrow cells resulted in colonies in the plasma clot containing only granulocytes and macrophages. Cyclophosphamide-treated host animals were essential for human CFU-D-G development. Plating efficiency for human marrow myeloid colonies was better in the conventional in vitro agar cultures than in diffusion chambers.

Malignant histiocytosis. A clinical and morphological study of four cases

Four patients with malignant histiocytosis are described. Major clinical signs were fever, lymphadenopathy, hepatomegaly and splenomegaly. Laboratory studies showed leukopenia, thrombocytopenia, low leukocyte alkaline phosphatase (LAP) score, normal erythrocyte sedimentation rate (ESR) and elevated serum triglycerides. There was evidence of bone marrow involvement in all four cases. Typical changes were seen in the histological study.

Thyroid function in rats administered excess iodide

The effects of excess iodide on the histology and function of the thyroid were studied in rats. A slight increase in thyroid weight and minimal histological alterations were observed. The thyroid function of rats was studied by measuring the serum total and free thyroxine. Excess iodide did not significantly change the concentration of thyroid hormone in the serum and signs of hypothyroidism were not seen. Thus, rats were capable of adaptation to chronic administration of large amounts of iodide. A slight increase in the serum thyrotrophin after prolonged ingestion of excess iodide was measured with both bioassay and radioimmunoassay techniques. The possible role of thyrotrophin in the mechanism of escape from the transient inhibition of iodide on thyroid hormone synthesis is discussed.