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T Mandel

Publications and source records attributed to T Mandel.

At least 55 records · Page 3Linked to original sources
PubMed1985

Are any functionally mature cells of medullary phenotype located in the thymus cortex?

Experiments were undertaken to test if thymocytes of "mature" or "medullary" phenotype were restricted to the medullary area of the thymus. A calculation based on direct cell counts on serial sections indicated that 11.5% of adult male CBA thymic lymphoid cells were within the medullary zone. Since only 3-4% of thymocytes were cortisone resistant, the majority of thymocytes within the medulla were, like cortical thymocytes, cortisone sensitive. A series of cell surface antigenic markers, used alone or in pairs, suggested that 13-15% of thymocytes were of medullary phenotype, somewhat more than the number of thymocytes actually present in the medulla. However, much of this discrepancy could be explained by differential death of cortical cells during isolation and staining, and by the existence in the cortex of a subpopulation of early blast cells which shared some, but not all markers with medullary thymocytes. A direct test for mature or medullary phenotype cells in the cortex involved selective transcapsular labeling of outer-cortical cells with fluorescent dyes, followed by multiparameter immunofluorescent analysis of the 10% labeled population. Outer-cortical thymocytes included some cells (mainly early blasts) sharing some markers with medullary thymocytes, but very few (less than 1%) of these cells expressed all the characteristic "mature" markers. Limit-dilution precursor frequency studies showed the level of functional cells in the outer cortex was extremely low. The overall conclusion was that the vast majority of cells of complete "mature" phenotype are confined to the thymic medulla. These findings favor the view that thymus migrants originate from the thymic medulla, but do not exclude a cortical origin. The results also illustrate the need for multiparameter analysis to distinguish medullary thymocytes from early blast cells.

Animals↗
PubMed1984

DR4 related antisera pattern differences in insulin dependent diabetes mellitus and rheumatoid arthritis.

Three allosera patterns of reactivity are described which appear to define subtypes of DR4 and segregate in families with different DR4 bearing haplotypes. There appears to be a preponderance of one particular subtype (termed DR4.3) occurring in type I insulin dependent diabetes mellitus, while in rheumatoid arthritis the distribution of subtypes within DR4 individuals is similar to that seen in controls. Although we refer to DR4 subtypes the proof that these sera are detecting a determinant on the DR molecule and not a product of another locus, an allele of which is linkage disequilibrium with DR4, awaits immunochemical confirmation.

Arthritis, Rheumatoid↗
PubMed1983

Electrophoretic comparison of cellular and soluble galactosyltransferase (lactose synthetase A protein) using specific antibodies.

Rabbit antisera against soluble human milk galactosyltransferase (GT) having anti-GT activity, as demonstrated by inhibition of enzyme activity were used for a comparative study of the molecular sizes of galactosyltransferase. For this purpose, affinity-purified antibodies were used for the identification of milk, serum and effusion galactosyltransferase from native or partially purified preparations resolved by sodium dodecyl sulfate polyacrylamide electrophoresis (SDS-PAGE) by the immune replica technique. Milk galactosyltransferase migrated as a 55-kilodalton (kD) protein, serum and effusion GT slightly faster. Cross-reactive enzyme forms of 110 kD and 20 kD were detected in milk only. In order to establish a relationship between intracellular and soluble galactosyltransferase, HeLa cells were metabolically labeled by [35S]-methionine, cells lysed, subjected to immunoprecipitation and the precipitate analyzed by SDS-PAGE/fluorography: a single band corresponding to the intracellular form of GT have similar mobility as the milk enzyme was detected. These results indicate a close structural similarity between soluble and cellular galactosyltransferase as judged by immunological cross-reactivity and electrophoretic mobility.

Animals↗
PubMed1982

A solid-phase ELISA for human galactosyltransferase.

Monospecific rabbit anti-human milk galactosyltransferase antibodies were used to develop a solid-phase enzyme-linked immunosorbent assay (ELISA) for the human milk enzyme. The assay was based on competition with galactosyltransferase-phosphatase conjugate. The detection limit of the standard curve was 30 ng/ml. Galactosyltransferase was quantified in dialyzed milk samples by ELISA with variation coefficients of less than 7.7% and between 6.8 and 18.8% within and between assays, respectively. The average content was 61 +/- 19 microgram/ml. The assay proved suitable for quantitation of partially purified enzyme preparations in body fluids.

Animals↗
PubMed1981

Immunohistochemical localization of galactosyltransferase in human fibroblasts and HeLa cells.

Anti-human galactosyltransferase (E.C. 2.4.1.22) antibodies were elicited in rabbits and purified on a galactosyltransferase-agarose column. Purified antibodies were used to localize galactosyltransferase in acetone-fixed HeLa cells and human lung fibroblasts. Both protein A-peroxidase developed with 3-amino 9-ethylcarbazole and swine anti-rabbit IgG-fluorescein isothiocyanate served to detect binding of anti-galactosyltransferase antibodies. In cells of confluent cultures, anti-galactosyltransferase staining appeared as a concise triangular structure in the juxtanuclear region with one angle oriented toward the bulk of the cytoplasm. The stained structure appeared as a dense cap on the nucleus in HeLa cells and as a more extended granular structure in fibroblasts. In cells of sparse cultures, specific anti-galactosyltransferase staining appeared in both HeLa cells and fibroblasts as a granular, extended structure, which was occasionally perinuclear. There was no evidence of cell surface localization of galactosyltransferase by light microscopy. The positively stained structures are interpreted to be part of the Golgi complex.

Antibodies↗
PubMed1980

Analysis of rat hemopoietic cells on the fluorescence-activated cell sorter. I. Isolation of pluripotent hemopoietic stem cells and granulocyte-macrophage progenitor cells.

A scheme is presented whereby pluripotent hemopoietic stem cells (PHSC) from rat bone marrow can be enriched 320-fold with the aid of the fluorescence- activated cell sorter. This scheme is based on the observations that PHSC are strongly positive for Thy-1 antigen (upper 10th percentile); have light- scattering properties (size distribution) between those of bone marrow lymphocytes and myeloid progenitor cells; and are relatively resistant to cortisone. It is estimated that PHSC may constitute 80 percent of the cells isolated according to these parameters. Candidate PHSC are described at the light and electron microscopic levels. At least two populations of accessory cells appear to influence the number and/or the nature of the hemopoietic colonies that form in the in vivo spleen colony-forming unit assay. Putative amplifier cells are strongly Thy-1(+) and cortisone sensitive; putative suppressor cells are weakly Thy-1(+) and cortisone resistant. Three subsets of granulocyte (G) -macrophage (M) progenitor cells (in vitro colony-forming cells [CFC]) are identified on the basis of relative fluorescence intensity for Thy-1 antigen: G-CFC are strongly Thy-l(+); M-CFC are weakly Thy-l(+); and cells that produce mixed G and M CFC have intermediate levels of Thy-1. GM-cluster-forming cells and mature G and M are Thy-1(-). The results suggest that G-CFC are bipotential cells that give rise to G and M-CFC; and that the latter produce mature M through a cluster- forming cell intermediate. Thy-1 antigen is also demonstrated on members of the eosinophil, megakaryocyte, erythrocyte, and lymphocyte cell series in rat bone marrow. In each instance, the relative concentration of Thy-1 antigen is inversely related to the state of cellular differentiation.

Animals↗
PubMed1980

Analysis of rat hemopoietic cells on the fluorescence-activated cell sorter. II. Isolation of terminal deoxynucleotidyl transferase-positive cells.

A method is described by which highly enriched populations of viable terminal deoxynucleotidyl transferase-positive (TdT+) cells can be isolated from rat bone marrow by use of the fluorescence-activated cell sorter. Such cells have been postulated to be progenitors of thymocytes and, possibly, of B lymphocytes, and may serve as the targets of neoplastic transformation in acute lymphoblastic leukemia. The separation procedure is based on differences in relative low-angle light scatter and relative fluorescence intensity for Thy-1 antigen between TdT+ cells and other lymphohemopoietic cell populations in bone marrow. Simultaneous sorting of bone marrow cells according to these two parameters resulted in a mean 87% purification of TdT+ cells. The morphological characteristics of the isolated TdT+ cells are described at the light and electron miscroscopic levels.

Animals↗
PubMed1972

A receptor for antibody on B lymphocytes. II. Immunochemical and electron microscopy characteristics.

Binding of antibody to the surface of B lymphocytes was shown to involve the Fc piece of the immunoglobulin molecule. This property was not shared equally by all immunoglobulin classes as revealed by direct binding and inhibition studies. Total IgG globulin was found to label cells more heavily than IgM, and IgG1-containing fractions more heavily than IgG2 fractions lacking IgG1. The ability of various purified myeloma proteins to inhibit attachment of antibody to B cells was examined. Pretreatment of B cells with excess IgG(2a), IgA, or light chain proteins failed to inhibit, whereas IgG1 proteins and to a lesser extent Ig(2b) and IgM proteins at the same concentrations did so. At lower protein concentrations, IgG1 myeloma protein alone retained the capacity to inhibit binding. The conclusion was reached that the receptor on B cells for antibody has a marked predilection for the IgG1 class. Although IgM and IgG(2b) antibody may bind, they do so with lower avidity and probably in insignificant amounts if IgG1 antibody is present in excess. No evidence was found to implicate complement in the binding process. For example, heat-inactivated sera at high dilution retained the ability to label B cells, while the use of purified low molecular weight anticomplementary factor, a potent inhibitor of C'3, did not interfere with the formation of the bond between antibody and cell surface. The failure of anti-mouse immunoglobulin F(ab)'(2) fragments to prevent access of antibody to B cells implied that the antibody-binding receptor and antigen-binding (immunoglobulin) receptor are discrete entities on the B cell membrane. Despite this, a marked similarity between their surface distribution was observed on electron microscopy. The antibody-binding receptor was shown to be a marker for mature B cells. It did not appear to be present on hematopoietic precursor stem cells and was lost during differentiation to antibody-forming cells.

Animals↗