Magnetic resonance imaging and 67gallium scan in mediastinal malignant lymphoma: a prospective pilot study.

BACKGROUND: A residual mediastinal mass is common after treatment for bulky mediastinal lymphoma and represents a difficult diagnostic problem. PATIENTS AND METHODS: 19 patients with bulky mediastinal masses due to malignant lymphoma had computed tomography (CT), magnetic resonance imaging (MRI) and 67Gallium scan (67Ga) before treatment, after four cycles of chemotherapy, and two, six and twelve months after end of treatment. RESULTS: MRI and 67Ga showed active tumor in all patients before treatment. Twelve months after treatment full consistency was found between the results of the two techniques. During treatment and the first six months after treatment, the two techniques were not in accord in some patients, partly due to later normalization of MRI compared with 67Ga. CONCLUSION: Both MRI and 67Ga are useful in assessing tumor activity in lymphoma mediastinal masses.

Delineation of subsets in human B-cell lymphomas by a set of monoclonal antibodies raised against B lymphoma cells.

Murine hybridoma antibodies to a human B-cell lymphoma were developed. After screening against normal T cells, monocytes, and granulocytes 11 antibodies that reacted with cells from other B-cell lymphomas remained, of which 10 showed individually distinct staining patterns, as tested by indirect fluorescence. When tested against lymphomas or cell lines, none of these antibodies revealed staining patterns suggesting reactivity with conventional B-cell surface markers, such as immunoglobulin, complement factor 3 receptors, or HLA-DR antigens. Only one of the antibodies (GB1) reacted with human serum, as determined by a blocking assay. The antibodies were found to belong to different immunoglobulin isotypes. Two antibodies (GB13 and GB14) reacted with greater than 5% of normal peripheral blood mononuclear cells. These reactions were mainly due to reactivity with B cells. The antibodies reacted only in a few cases with acute leukaemias, B-cell lines, and follicular lymphomas. On the other hand, distinct patterns of reactivity in different histological groups of diffuse lymphomas were obtained, suggesting that the antibodies may be useful in delineating phenotypic subsets among human B-cell lymphomas.

Morphology of mouse epidermal cells in vitro: a scanning electron microscopy study.

Scanning electron microscopy of isolated epidermal cells from newborn mice grown in vitro showed that the cultures consisted of several morphologically different types of cells. Young cultures had many smooth, round cells while older cultures contained more cells with rough or ruffled surface and a varying number of flat, irregular cells. Probably, the various cell types corresponded to different stages of differentation (keratinization). Cultures that were grown in the presence of retinyl acetate (12.5 microgram/ml) had more round and smooth cells after several days in vitro than the controls. This could indicate that retinyl acetate delayed or altered cell differentiation. Scanning electron microscopy of the cultures consistently showed that the cells were situated at different layers. The apparent monolayer seen by phase contrast microscopy therefore seems to be an optical phenomenon due to projection of the cells onto the same plane.

Platelets, endothelial cells and macrophages in the spleen. An ultrastructural study on perfusion-fixed organs.

Rabbit spleens have been examined after perfusion fixation with and without prior washing with various fluids. The platelets were stored in the splenic sinuses and in the cord spaces as single platelets, or in loosely packed aggregates which appeared to be anchored to the endothelium by one or a few platelets. After washing prior to fixation most of the platelets disaggregated and regained their normal shape. Some platelets adhered to morphologically normal endothelium even after prolonged perfusion. Occasionally, platelets were observed inside splenic endothelial cells. Others were closely associated with macrophages, many of which also contained engulfed platelets. There was no morphological evidence of a particular platelet population being retained in the spleen after washing. In the sinuses special granule-rich cytoplasmic structures were observed. They were interposed between ordinary endothelial cells and contained a large number of small lysosome-like granules. Nuclei were never observed in these structures, probably because they consisted of pseudopod-like protrusions. Their origin and function are discussed. They may represent actively phagocytizing elements.

Ultrastructural identification of umbilical cord vein endothelium in situ and in culture.

The ultrastructure of human umbilical cord vein endothelium in situ, after isolation by collagenase treatment, and in primary culture is described. The cultured cells formed a monolayer with typical "butt" and interdigitated junctions with specialized areas, and contained Weibel-Palade bodies, rod-shaped tubular organelles considered specific of endothelial cells. These morphological features were not present in cultures of human skin fibroblasts and fibroblast-like cells derived from umbilical cords. It is thus concluded that endothelial cells retain their characteristic fine structure in primary culture. Simple ultrastructural studies can thus be used to identify endothelial cells in culture.

Human fetal endothelial cells in cluture.

Human endothelial cells were isolated from the umbilical cord vein by collagenase treatment and cultured for periods up to 6 weeks. The cultured cells were identified as endothelium by cell morphology and growth pattern, the presence of Weibel-Palade bodies, and their ability to stimulate allogeneic lymphocytes (Hirschberg et al 1974). Cultured fibroblast-like cells derived from the umbilical cord were clearly different in all three respects. Approximately one third of the primary endothelial cultures showed clear evidence of proliferation during the first 3-4 days in culture as judged by cell counting. Replicating ability in a culture was correlated with cell density at the time of seeding. Autoradiography of endothelial cells after exposure to 3-H-thymidine showed a 30-fold increase in nuclear labelling from day 1 to day 3 in culture. The endothelial cells have so far been subcultured three times.