Ultrastructural features of CD34+ hematopoietic progenitor cells from bone marrow, peripheral blood and umbilical cord blood.

Hematopoietic progenitor cells from different sources have been widely characterized, but their ultrastructural morphology has never been described in detail. In this study, imunomagnetically separated CD34+ cells from normal bone marrow (BM), mobilized peripheral blood (PBSC) and human umbilical cord blood (CB) were studied by transmission electron microscopy (TEM) using a cytochemical method which reveals endogenous myelo-peroxidase (MPO) activity. This technique is particularly suited for detecting early signs of the myeloid commitment.

Functional and morphological characterization of immunomagnetically selected CD34+ hematopoietic progenitor cells.

We evaluated the potential of immunomagnetically selected (miniMACS) progenitor cells to give rise to colony-forming cells and their precursors, detected as long-term culture-initiating cells (LTC-IC), as well as their capacity to expand in liquid cultures. A 90% mean purity, a 43.2% yield and a 55.

Ultrastructural studies of the megakaryoblastic leukemias of Down syndrome.

The ultrastructure of the leukemic cells in transient leukemia (six cases), myelodysplasia (five cases) and acute megakaryoblastic leukemia (one case) in patients with Down syndrome were studied. The cells were identified to be of megakaryocytic lineage by virtue of the expression of platelet glycoprotein GpIIIa, detected by immunogold labelling. In all patients, some of the leukemic cells had ultrastructural features of megakaryocytes, including ectoplasmic protrusions, demarcation membranes, and alpha granules.

Cell surface changes of hemopoietic cells during normal and leukemic differentiation: an immuno-scanning electron microscopy study.

Hemopoietic cells display a wide range of cell surface antigens which are either lineage specific or acquired during differentiation. Monoclonal antibodies can be used, in conjunction with colloidal gold markers, to identify under the scanning electron microscopy (SEM) at the single cell level, specific lineage or maturation stages in the hemopoietic bone marrow. Normal bone marrow cells, either gradient separated or purified by immuno-magnetic methods and leukemic cell samples, which can be considered as "frozen" stages of hemopoietic differentiation, have been studied with this method.

Immuno-electron microscopy characterization of human bone marrow stromal cells with anti-NGFR antibodies.

Human bone marrow stromal cells have been examined with an immuno-electron microscopy technique in order to better define their structure and function in normal hematopoiesis. Bone marrow fragments from normal donors, after mild permeabilization and glutaraldehyde prefixation were labeled with the Me20.4 Mab, which recognizes the low affinity nerve growth factor (NGFR) and was recently described as specifically identifying fibroblastic-like bone marrow stromal cells.

Immunogold labeling for the diagnosis of leukemia by transmission and scanning electron microscopy.

For the cell type diagnosis of leukemia in adult patients, particularly when the sampling of bone marrow is difficult, the study of peripheral blood leukocytes (PBLs) by immuno-electron microscopy provides significant information, as illustrated here in two cases of hairy cell leukemia and seven cases tentatively identified as megakaryoblastic leukemia (M7). Indirect immunogold labeling with the B-ly7 monoclonal antibody (CD103) proved valuable in confirming the diagnosis of hairy cell leukemia. Immunogold labeling for the GpIIIa platelet glycoprotein (CD61) was used in cases where the light microscopy of blood films revealed possible megakaryoblastic leukemia.

Immunogold labelling of leukemic hairy cells with the B-ly7 monoclonal antibody: an SEM and TEM study.

Two cases of hairy cell leukemia have been studied by immuno-TEM and immuno-SEM after immunogold labelling of the cell surface antigen recognized by the B-ly7 monoclonal antibody. Most hairy cells appeared significantly labeled, although the density of the expression of the antigen, as demonstrated by immunogold labelling, seems variable from cell to cell. Moreover, some cells with the morphology of hairy cells and which could not be identified as monocytes were not labeled.

Myelodysplasia and acute megakaryoblastic leukemia in Down's syndrome.

In this report we describe the clinical and hematologic features of 23 cases of myelodysplasia (MDS) or acute megakaryoblastic leukemia (AMKL) occurring in Down's syndrome. MDS was characterized by thrombocytopenia, abnormal megakaryocytopoiesis, megakaryoblasts (< 30%) in the marrow and abnormal karyotype, the most common of which was trisomy 8, found in 7/15 patients with MDS. Three of five patients achieved a complete remission with low dose cytosine arabinoside, vincristine and retinyl palmitate.

Cell type identification in leukemia: the level of agreement among four independent diagnostic methods.

The level of agreement among four independent diagnostic methods for cell-type identification in leukemia was examined. The four diagnostic methods were routine morphology, electron microscopy, cell surface marker analysis by flow cytometry, and cancer cytogenetics. Sixty-five blood and bone marrow samples from fifty-seven patients were independently investigated by the four methods.

Human chromosomes: evaluation of processing techniques for scanning electron microscopy.

Methods for scanning electron microscopy (SEM) of chromosomes have been developed in the last two decades. Technical limitations in the study of human chromosomes, however, have hindered the routine use of SEM in clinical and experimental human cytogenetics. We compared different methodologies, including metal impregnation, air drying and specimen coating.

Antibody drug carrier for immunotherapy of superficial bladder cancer: ultrastructural studies.

Superficial bladder cancer represents a promising target for intravesical, antibody-guided therapy. The construction of an optimum antibody-cytotoxic drug conjugate depends mostly on the appropriate selection of a monoclonal antibody (mAb). We have used immunogold labeling and SEM to specifically map the distribution of antigens expressed on three bladder cancer cell lines and on the luminal surface of biopsies from human transitional cell carcinoma of various grades and from normal bladder mucosa.

Immunogold labeling of the low-affinity (55 kd) IL2 receptor on the surface of IL2 receptor-bearing cultured cells and mitogen-activated peripheral blood lymphocytes.

Foreign antigens or mitogens initiate activation of T lymphocytes through antigen-specific receptors. After antigen-receptor interaction, T cells release a lymphotrophic hormone, interleukin 2 (IL2), and high-affinity IL2 receptors (IL2R) are progressively expressed on their surfaces. When evaluated under the scanning electron microscope after specific immunolabeling with colloidal gold markers, the density of expression of the 55 kd low-affinity IL2 receptor (Tac) increases in a time-dependent manner, reaching a maximum 72 hours after the onset of phytohemagglutinin (PHA) activation.

Scanning electron microscopy of immuno-gold labeled antigens associated with bladder cancer.

Scanning electron microscopy (SEM), in the backscattered electron imaging (BEI) mode, has been used to study the topographical distribution of colloidal gold labeled antigens expressed on the luminal surface of the bladder urothelium in biopsies from three categories of patients: 1) normal controls; 2) patients with a history of bladder cancer but no pathological diagnosis at time of cystoscopy; and 3) patients with overt transitional cell carcinoma (TCC) of various histopathological stages and grades. Cold cup biopsies were processed for immuno-SEM according to a previously described method. Antigens under investigation were: 1) ABH blood group antigens; and 2) those identified by the following murine monoclonal antibodies (mAbs): LEU-M1, T16, 19A211, G4 and E7.

Scanning electron microscopic study of immunogold-labeled human leukocytes.

For many years critical point drying (CPD) has been the method of choice for preparing cells for scanning electron microscopy (SEM). Described herein is a simple, efficient, inexpensive, reproducible, and safe procedure using Peldri II, a proprietary fluorocarbon compound that is solid at room temperature and a liquid above 25 degrees C, as a sublimation dehydrant for processing specimens for SEM. The utility of Peldri II was demonstrated in studies using leukocytes from the blood of healthy donors and patients with leukemia as well as from long-term lymphoblastoid cell lines.

Double labelling of cell surface antigens with colloidal gold markers.

Particles of colloidal gold of different diameters (15 nm and 40) have been used to distinctively label different surface antigens expressed on the surface of human peripheral blood B and T lymphocytes. Silver enhancement has been used to facilitate the observation of the gold particles. Observations were carried out in the backscattered electron imaging mode of the scanning electron microscope.

The Surface Phenotype of Lymphatic Leukemia, Cells: An Immunoscanning Electron Microscopy Study.

Bone-marrow cells from 11 cases of T- and 18 cases of B-lymphatic leukemia, at different maturation stages, were examined by scanning electron microscope (SEMI. All cases were extensively studied for the expression of surface markers by immunofluorescence. In addition six cases of T- and 10 cases of B-cell leukemia were labeled with a panel of monoclon;tl antibodies (including CD3, CD5, CD7, CD10, CD4, CD8, CD19, CD20 and CD22) and, after incubation with a colloidal gold conjugate, observed with SEM in the back-scattered electron imaging mode.

Malignant properties of sublines selected from a human bladder cancer cell line that contains an activated c-Ha-ras oncogene.

The human bladder cancer cell line MGH-U1 (also designated T-24 or EJ) contains an activated c-Ha-ras oncogene, which is amplified as compared to normal human fibroblasts. We have generated sublines from the MGH-U1 cell line: the MGH-U1/OCI subline was generated by dissociating spheroids formed from MGH-U1 cells; the U1-m/F1 and OCI-m/F1 were generated by in vivo passage of experimental lung metastases formed after i.v.

Phenotypically heterogeneous deletion of the ABH antigen from the transformed bladder urothelium. A scanning electron microscope study.

The deletion of ABH blood group antigens from the luminal surface of the bladder mucosa in cases of well differentiated transitional cell carcinomata, and the formation of pleomorphic microvilli have both been associated with aggressive biological behaviour and invasiveness of the tumors. We have studied cold cup biopsies from 8 normal mucosae and 17 papillary transitional cell carcinomata of the urinary bladder. The aim of our study was to correlate the formation of uniform or pleomorphic microvilli with the extent of deletion of the ABH blood group antigens on the surface of normal and transformed bladder urothelium.

Immunogold labeling of human leukocytes for scanning electron microscopy and light microscopy: quantitative aspects of the methodology.

When cell surface antigens are labeled with the colloidal gold marker, back-scattered electron images (BEI) reveal all the gold particles and, therefore, permit total counts. Secondary electron images (SEI) show only a small percentage of the gold particles and are inadequate for quantitative evaluation. For determination of the cellular labeling index, a time-consuming method implies the screening of 100 cells by scanning electron microscopy, at a magnification of approximately 12,000 to 15,000x, with continuous SE/BE shifts.