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Biomedical subjects

F A Spring

Publications and source records attributed to F A Spring.

29 records · Page 2Linked to original sources
PubMed1990

Preferential expression of the complement regulatory protein decay accelerating factor at the fetomaternal interface during human pregnancy.

The expression of decay accelerating factor (DAF) was investigated in human fetal and extra-fetal tissues using a panel of mAb directed against different epitopes on the DAF molecule. By immunostaining, extensive reactivity was observed on the placental trophoblast epithelium and this was confined exclusively to sites of direct contact with maternal blood and tissues at the fetomaternal interface. Within the fetus, by contrast, very little staining was observed especially on hemopoietic cell populations in the developing liver. The antibodies identified a component of 70,000 m.w., comigrating on SDS-PAGE with red cell DAF, on isolated trophoblast membranes and an apparently quantitative increase in the expression of DAF was observed during placental development. Northern analysis using a DAF cDNA clone revealed 1.5-, 1.6-, and 2.2-kb mRNA transcripts typical of DAF in mRNA prepared from whole term placentae and from purified trophoblast cells. DAF appears to be preferentially expressed at the fetomaternal interface during development and may function specifically to inhibit amplification convertases formed at this site either directly or indirectly as a result of maternal complement activation. This molecule may play an important role in protecting the semiallogeneic human conceptus from maternal C-mediated attack.

Antibodies, Monoclonal↗
PubMed1990

An erythrocyte glycoprotein of apparent Mr 60,000 expresses the Sc1 and Sc2 antigens.

Immunoblotting with human anti-Sc1 and anti-Sc2 locates the Sc1 and Sc2 antigens to an erythrocyte membrane glycoprotein of apparent Mr 60,000. The antigens are destroyed by pronase, and require intact disulphide bonds for expression. A proportion of the molecules carrying the Sc1 and Sc2 antigens are associated with red cell cytoskeleton preparations. Treatment of intact cells with an Endo F preparation resulted in the loss of the Sc2 antigen but not the Sc1 antigen, suggesting that the Sc2 antigen is dependent on the presence of one or more complex N-glycans for its expression.

Blood Group Antigens↗
PubMed1988

The Ina and Inb blood group antigens are located on a glycoprotein of 80,000 MW (the CDw44 glycoprotein) whose expression is influenced by the In(Lu) gene.

The Ina and Inb blood group antigens were found to be located on an erythrocyte membrane glycoprotein of 80,000 MW by immunoblotting with human anti-Ina and anti-Inb antibodies under non-reducing conditions. This glycoprotein is shown here to be identical to that defined by monoclonal antibodies to CDw44, and a new murine monoclonal antibody (BRIC 35) is added to this cluster. Experiments with endo-beta-galactosidase and Endo F preparations suggest that the glycoprotein contains one or more N-glycans but that these oligosaccharides do not contain extensive poly-N-acetyllactosaminyl sequences. Experiments using membranes prepared from sialidase-treated normal erythrocytes, from Tn erythrocytes and from Cad erythrocytes suggest that the glycoprotein does not contain a substantial content of O-glycans. The Inb antigen and the epitope defined by a murine monoclonal antibody (BRIC 35) show reduced expression on Lu(a-b-) erythrocytes which result from the effect of the dominant inhibitor gene In(Lu). Evidence is presented here that the Inb antigen is expressed on normal granulocytes and lymphocytes and on the haemopoietic cell lines HEL, K562 and HL-60, a lymphoblastoid cell line and lymphocytes from two patients with B-CLL.

Antibodies, Monoclonal↗
PubMed1987

A human cell-surface glycoprotein that carries Cromer-related blood group antigens on erythrocytes and is also expressed on leucocytes and platelets.

A new human erythrocyte glycoprotein has been identified by immunoblotting with murine monoclonal antibodies under non-reducing conditions. The glycoprotein has a MW of 70,000 and carries Cromer-related blood group antigens. The monoclonal antibodies also react with normal peripheral blood leucocytes and platelets and several haemopoietic cell lines. The glycoprotein has a reduced MW after sialidase treatment. The MW is markedly reduced in Tn erythrocyte membranes and slightly increased in Cad erythrocyte membranes. These results suggest that the glycoprotein has a substantial content of O-glycans. The glycoprotein appears to be absent from, or grossly altered in, the erythrocytes of two individuals with the rare Inab phenotype.

Antibodies, Monoclonal↗
PubMed1983

Lectin-binding components of normal granulocytes and leukaemic myeloid cells.

A panel of lectins was used to analyse glycoproteins of normal granulocytes and leukaemic myeloid cells. The glycoproteins of detergent-solubilized whole cells were separated by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis and their lectin-binding properties determined by incubation of the fixed gels with radioiodinated lectins. Normal granulocytes and leukaemic myeloid cells in different stages of maturation possess a cell-surface sialic acid-rich glycoprotein of apparent mol.wt. 115 000 (GP115), that can be labelled by both the lactoperoxidase and periodate/NaB3H4 cell-surface labelling techniques. The sialoglycoprotein of leukaemic myeloblasts has a slightly lower apparent mol.wt., 112000 (GP112). After neuraminidase treatment before cell solubilization, both GP115 and GP112 bind the lectins from Arachis hypogaea (peanut) and Helix pomatia (snail) and have an increased apparent molecular weight of 125000. Two concanavalin A-binding glycoproteins of apparent mol.wts. 98000 and 90000 are present in leukaemic myeloblasts. Concanavalin A binding to these glycoproteins is decreased in more mature leukaemic cells and absent in granulocytes. As concanavalin A binding decreases in the maturer forms, there is a concomitant increase in the binding of Ricinus communis (castor bean) and Maclura aurantiaca (osage orange) lectins to these glycoproteins. Whole granulocytes, but not leukaemic myeloblasts, contain a major cell-surface concanavalin A binding glycoprotein of apparent mol.wt. 130000, which is labelled by the periodate/NaB3H4 technique. Concanavalin A binding to this glycoprotein increases as the morphology of leukaemic cells approaches that of mature granulocytes.

Cell Membrane↗
PubMed1983

Evidence for carbohydrate-deficient forms of the major sialoglycoproteins of human platelets, granulocytes and T lymphocytes in individuals with Tn syndrome.

125I-Helix pomatia and 125I-wheat germ lectins were used as probes to visualise membrane glycoproteins of circulating blood cells from individuals with Tn syndrome. Cells were solubilized in Triton X-100 and subjected to sodium dodecyl sulphate polyacrylamide gel electrophoresis prior to incubation with iodinated lectins. Normal platelets, granulocytes and T lymphocytes have a single major sialoglycoprotein of mol. wt. 143,000, 115,000 and 115,000 respectively. In Tn platelets, granulocytes and T lymphocytes there was a marked reduction in lectin binding in the region of the sialoglycoproteins but new lectin binding components of lower mol. wt. (125,000, 98,000 and 98,000 respectively) were apparent. It is suggested that these new lectin binding components are the sialoglycoproteins with deficient glycosylation resulting from the known deficiency of beta-3-galactosyltransferase in Tn syndrome.

Blood Platelets↗