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T An

Publications and source records attributed to T An.

50 records · Page 3Linked to original sources
PubMed1981

Natural clusterings of Fc receptors on human neutrophils--not affected by the cytoskeletal reagents.

By using sucrose density gradient ultracentrifugation and immunodiffusion, we confirmed the monovalency of the electron microscopic ligand for the receptor for the Fc portion of IgG (FcR) on human neutrophils, which was composed of one ferritin (Fer) molecule and one IgG anti-Fer molecule. Pre-treatment of neutrophils at 37 degrees for 30 min with cytochalasin B, colchicine, both of the reagents, concanavalin A, and tetracaine did not alter the clustering of FcR on the surface, which was demonstrated by the ligand at 0 degrees. The effectiveness of these employed cytoskeletal reagents was determined ultrastructurally by observing the changes of morphology and cytoskeletal structures of treated neutrophils; a novel and unique cellular change of cytochalasin B-treated neutrophils was described which we called arachnocytosis. Under our experimental conditions the cytoplasmic surface of the membrane under the receptor patches did not show any specialized density resembling coated membrane regions. These data verify our previous finding that FeR is naturally clustered on human neutrophils, and suggest strongly that the FcR natural clustering is not primarily mediated by the cytoskeletons consisting of microfilaments (actin) and microtubules, and the coated membrane region. The exact mechanism for FcR clustering on human neutrophils is not clear and remains to be elucidated.

Colchicine↗
PubMed1980

Binding of soluble immune complexes to Fc receptors on human neutrophils--detection by double-coating indirect rosette formation.

By using double-coating indirect rosette formation (DIRF), which is a modification of Coomb's mixed antiglobulin reaction, soluble immune complexes of ferritin (Fer) and rabbit anti-Fer in 40- to 120-fold antigen excess are shown to bind to the Fc receptor (FcR) on human neutrophils and lymphocytes. The molar ratios of anti-Fer antibody and Fer in these immune complexes are determined, at least, 1:7 and 1:21 respectively. These immune complexes have the same capabilities in detecting FcR-bearing neutrophils and lymphocytes, which is dependent upon the amounts of anti-Fer antibody present in the complexes. 81% on average of human neutrophils bear FcR which is trypsin resistant. The FcR on neutrophils is partially sensitive to pronase and completely inactivated after short glutaraldehyde fixation at 0 degrees C of the cells. Our findings strongly suggest that the weak binding of soluble immune complexes in antigen excess in some studies reflected the limitation of techniques employed to detect the binding rather than the nature of FcR on phagocytes.

Antigen-Antibody Complex↗
PubMed1980

Fc receptors on human neutrophils: electron microscopic study of natural surface distribution.

The membrane receptor for the Fc portions of IgG (FcR) was examined on the cell surface of human neutrophils using electron microscopic markers of soluble immune complexes composed of ferritin (Fer) and rabbit 7S anti-Fer prepared in forty-fold and 120-fold antigen excess than needed at equivalence. By using negative staining coupled with electron microscopy, most of the immune complexes in forty-fold antigen excess were seen to be composed of one anti-Fer antibody and one or two Fer particles, suggesting that most of the indicator molecules are 'monovalent ligands' in terms of Fc pieces available per single immune complex molecule. FcR on neutrophils labelled with both indicators at 0 degrees in the presence of sodium azide were clustered as discontinuous patches of varying length over the cell surface. The pre-incubation of neutrophils at 37 degrees for 30 min prior to labelling did not alter the grouped distribution of FcR. No diffuse Fer labelling was observed. The clustering of FcR remained the same even after cross-linking the soluble complexes with F(ab')2 anti-Fer into multivalent ligands at 0 degrees. We favour the clustering of FcR as the natural surface representation on human neutrophils rather than an initial redistribution induced by the ligands. The findings are discussed with relation to the natural distribution of other surface antigens.

Antigen-Antibody Complex↗
PubMed1979

Fc receptors on human lymphocytes detected with double-coating indirect rosette formation.

The Fc receptor (FcR) on human lymphocytes is studied by using soluble immune complexes in antigen excess, prepared between ferritin and rabbit anti-ferritin, and a modification of Coombs' antigolbulin reaction (double-coating indirect rosette formation). 12% of human blood lymphocytes are shown to have Fc receptors. The FcR on lymphocytes is sensitive to pronase treatment, partially sensitive to trypsin digestion, and is inactivated after short glutaraldehyde fixation of lymphocytes. By cell fractionation experiments, FcR-positive lymphocytes were enriched in cell populations enriched with B cells.

Animals↗
PubMed1979

Electron microscopy of Fc receptors on human lymphocytes.

The membrane receptor for Fc portions of IgG (FcR) was localized on the cell surface of humans lymphocytes by electron microscopy. The electron microscopic markers for FcR were soluble ferritin 7S anti-ferritin immune complexes prepared in forty times antigen excess than needed at equivalence. Fc receptors on the lymphocytes labelled at 0 degree in the presence of sodium azide were seen as discontinuous patches on the cell surface. In control experiments, no labelling was observed, which included lymphocytes treated with ferritin only or with F(ab')2 immune complexes as well as glutaraldehyde-fixed lymphocytes treated with 7S anti-ferritin immune complexes. The findings are discussed with relation to the widely accepted membrane fluidity model.

Antigen-Antibody Complex↗
PubMed1978

Postirradiation sarcoma (malignant fibrous histiocytoma) of axilla.

A case is reported of a patient who developed a histologically unusual sarcoma in the axilla and chest wall 8 years after receiving radiation therapy (6500 rad) for carcinoma of the breast. This sarcoma showed light- and electron-microscopic features of a malignant fibrous histiocytoma, a tumor not documented among 24 previously reported cases of postirradiation sarcoma following the diagnosis of breast carcinoma. In addition, the literature is reviewed and discussed regarding postirradiation sarcoma in general following breast carcinoma.

Adult↗
PubMed1978

Amyloid formation in insulinoma.

Local amyloid depositions were investigated with electron microscopy in a functioning beta cell adenoma of the pancreas. Beta granule-containing neoplastic cells adjoining small amyloid depositions were shown to have cellular invaginations containing radiating amyloid bundles, indicating the neoplastic cells were involved in the formation of amyloid. Seen in the larger mayloid depositions were attenuated, thin, cellular processes of the neoplastic cells, separating the amyloid stroma into globules. The globular separations of the amyloid correlated well with the light-microscopic globular appearance of amyloid stroma. Possible mechanisms are discussed for the amyloid deposition of insulinoma with relation to amyloidogenesis of other types of amyloidosis.

Adenoma, Islet Cell↗