Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P02794 (ferritin)
 17,525 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mouse mesenteric lymph node cells were incubated in the soluble immune complexes of ferritin-antiferritin immunoglobulin G at 37 degrees C for 20 min. After being washed, postfixed with OsO4 and dehydrated by degraded ethanol series, the lymph node cells were observed by electron microscope. Apprroximately 15% of the cells (mainly composed of small lymphocytes) bound ferritin particles to the cell surface. The distribution pattern of the binding of ferritin particles (ferritin-antiferritin immunoglobulin G) took the form of discrete patches of irregular distribution interspaced with unlabeled portions. The electron microscopic features of ferritin particles (ferritin-antiferritin immunoglobulin G) attached to the cell surface suggest that a structure of constant conformation (Fc receptor) situated in the cell membrane takes part in the binding of ferritin-antiferritin immunoglobulin G.
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PMID:Immunohistochemical detection of Fc receptor. II. Electron microscopic demonstration of Fc receptor by using soluble immune complexes of ferritin-antiferritin immunoglobulin G. 40 52

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.
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PMID:Fc receptors on human lymphocytes detected with double-coating indirect rosette formation. 44 2

When 111In-labeled murine monoclonal antibodies are used in radio-scintigraphic diagnostic procedures, a large fraction of the injected radionuclide is sequestered by the liver. Neither the cells responsible for the uptake nor the mechanism of uptake are known. Little is known about either the site within the liver of antibody metabolism or the form of the products of metabolism. In these studies, the uptake and metabolism of a monoclonal antibody, B6.2 radiolabeled with 111In or 125I [either intact B6.2 or F(ab')2] were determined in rats. One h after injection of either 125I- or 111In-diethylenetriaminepentaacetic acid (111In-DTPA)-labeled B6.2, the predominant liver cell in which the radionuclide was found was the parenchymal cell. At this time, the absolute uptake of 125I in the liver was 0.23 +/- 0.06% (SD) of the injected dose compared to 0.61 +/- 0.06% when the radionuclide was 111In. Removal of the Fc portion of the antibody reduced the absolute liver uptake of 125I to 0.10 +/- 0.01 and the absolute uptake of 111In to 0.16 +/- 0.06. Both radionuclides were still associated predominantly with the parenchymal cell. Using size exclusion high performance liquid chromatography analysis of liver supernatants the metabolism of radiolabeled B6.2 was followed for 24 h. Of the radioactivity recovered, 47.9% of the 125I was precipitable by centrifugation (and presumed bound to cell membranes) while 15.4% was attached to B6.2 found in the cytosol. In contrast, when 111In-DTPA-B6.2 was administered, 16.0% of 111In recovered from the liver was precipitable by centrifugation, and 6.5% was attached to B6.2 found in the cytosol. Sixty % of the 111In was recovered as a low molecular weight (less than 1000) component in the cytosol. This metabolite was not immunoreactive, nor did it comigrate with ferritin, and was resolved into four components by ion exchange high performance liquid chromatography. Of these, only a minor component cochromatographed with an 111In-DTPA standard. These data suggest that the large accretion of radionuclide by the liver is due to uptake of monoclonal antibodies by an Fc receptor-mediated mechanism and the subsequent accumulation of low molecular weight metabolites, presumably 111In-DTPA, attached to one or more amino acids. The reasons for the entrapment of metabolites in the liver are under investigation.
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PMID:Uptake and metabolism of 111In-labeled monoclonal antibody B6.2 by the rat liver. 229 33

We have examined the effect of targeting an antigen to the immune system, by covalently coupling it to anti-immunoglobulin (Ig), on its efficacy for T cell stimulation in vitro and its immunogenicity for antibody production in vivo. In vitro, we compared the potency (for stimulation of a ferritin-specific T cell line) of free ferritin, ferritin coupled to goat antimouse IgM (heavy (H) chain specific), ferritin coupled to anti-IgG (H and light (L) chain specific), or ferritin coupled to anti-IgA (H chain specific), as well as a mixture of free ferritin plus goat anti-IgG. The ferritin coupled to anti-IgM or to anti-IgG (H + L), which could bind to surface Ig of B cells, stimulated T cell proliferation at concentrations of ferritin at least 10-fold lower than those required for the other forms of the antigen over the entire time course of the response, with 1000 rad-irradiated spleen cells as presenting cells. Because the goat antibodies were all of the same IgG isotype and coupling ratio, the failure of goat anti-IgA to enhance potency served as a control to exclude Fc receptor binding as the mechanism. The effect was not due to the nonspecific activation of B cells to become more efficient antigen-presenting cells, because mixtures of ferritin plus anti-IgG (H + L) had no effect, and the anti-IgG coupled to ferritin did not enhance presentation of myoglobin to a myoglobin-specific T cell line. The enhanced presentation of ferritin conjugated to goat anti-IgG (H + L) or to anti-IgM was sensitive to radiation doses greater than 2000 R, and was effective at less than one-tenth the number of spleen cells, consistent with the predominance of B cells as antigen-presenting cells for this form of the antigen rather than macrophages and dendritic cells only. When B cells and accessory cells were purified from T-depleted spleen cells, only the B cell preparation but not the accessory cell population manifested enhanced presentation of ferritin coupled to anti-IgG compared with free ferritin, and it was radiosensitive. Finally, allogeneic B cells could not mediate the enhancement in the presence of syngeneic splenic accessory cells (SAC); therefore, the enhancement was not due to shedding of immune complexes from B cells and subsequent presentation by SAC. We conclude that targeting the antigen to B cells as presenting cells greatly enhances its efficacy in vitro.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Enhancement of antigenic potency in vitro and immunogenicity in vivo by coupling the antigen to anti-immunoglobulin. 307 11

The IgG-Fc binding activity and binding sites on the cell surface of streptococci, strains AR1 (group A) and G148 (group G), and Staphylococcus aureus strain Cowan I were examined by hemagglutination (HA) and immunoelectron microscopic methods. No distinct difference was observed in the HA activity among these three strains. However, the strains differed in the distribution of Fc receptor. Cowan I cells (having protein A) were heavily covered with two layers of ferritin particles, whereas AR1 cells were heavily covered with a single, rough layer of ferritin particles. G148 cells (having protein G) were labeled with a relatively thin, rough ferritin layer. The trypsin susceptibility of the Fc receptors of the AR1 strain was much higher than that of the G148 strain. These results suggest that both streptococcal strains are distinctly different in the arrangement or in the conformation of the Fc receptor from the Cowan I strain. It is also suggested that the Fc receptor molecules of the streptococcal strains differ from each other not only in conformation but also in trypsin susceptibility.
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PMID:Hemagglutination activity and localization of Fc receptor of group A and G streptococci. 328 3

The so-called Potter's lesion, previously described as preneoplastic in the lymph nodes of C58 mice, develops frequently in autoimmune NZB mice. These lesions were characterized in the present study by bands or sheets of pale-staining histiocytic cells in the cortex and medulla of the lymph node, and multiple small nodules of the same cells were found in the red pulp of the spleen and the liver. Electron microscopically, the cells had pleomorphic cytoplasm with long processes, electron-dense bodies, abundant mitochondria, and a characteristic labyrinth structure with many C-type viruses. Mac-1 antigen, IgG-Fc receptor, ferritin, and ACPase activity were identified on these cells. Intraperitoneally-injected iron colloids were found in the lesions of the spleen and liver but not in those of the lymph nodes. The lymph node lesions appeared when the mice were about 3 months of age and enlarged until the mice were around 10 months old, after which they gradually receded and were replaced by small vessels and fibroblastic cells. These data indicate that the lesions represent reactive hyperplasia of the macrophage system and may have no direct association with the development of malignant lymphoma in NZB mice.
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PMID:Characteristics of histiocytic lesions in the reticuloendothelial system of NZB mice. 332 95

A fluorescein- and lactoperoxidase-conjugated ferritin-anti-ferritin immune complex has been prepared for cell surface labeling experiments on immune recognition and effector function. Lactoperoxidase (LPO) has been covalently coupled to affinity-purified anti-ferritin antibodies with p-benzoquinone by a modified version of the method of Ternynck and Avrameas [Ternynck, T., & Avrameas, S. (1976) Ann. Immunol. (Paris) 127C, 197]. The conjugate is a heterodimer of Mr230 000 with linkages to either or both of the heavy and light chains of the antibody, as judged by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) in the absence and presence of 2-mercaptoethanol. The conjugate retains antibody-binding activity as measured by a quantitative precipitin assay. When incorporated into immune complexes, the modified antibody also retains Fc receptor recognition ability as determined by erythrocyte-antibody rosette inhibition assays. Electron microscopy demonstrated that the antigen, ferritin, was monodisperse with complete apoprotein sheaths surrounding the core. Ferritin-anti-ferritin-LPO complexes were formed in 4-fold antigen excess. Complexes were verified by fluorescence and electron microscopy. Immune complexes were masked with "cold" iodine by use of the endogenous LPO activity. The complexes bound to cells at 4 degrees C as shown by electron microscopy and fluorescence video/intensification microscopy. The LPO delivered to the cell surface in this fashion can be utilized to iodinate the surface with 125I. Under saturation conditions, the labeling with local LPO delivery followed by SDS-PAGE and autoradiography is identical with labeling with free LPO. Labeling has also been conducted under conditions of substrate deficit.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Macrophage recognition of immune complexes: development and application of novel cell surface labeling procedures. 405 86

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.
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PMID:Binding of soluble immune complexes to Fc receptors on human neutrophils--detection by double-coating indirect rosette formation. 676 34

Multivalent hybrid antibody (MHA) complexes with dual specificity were prepared by combining two antibodies of different specificities, one against ferritin (Fer), the other against horseradish peroxidase (HRP), with protein A of Staphylococcus aureus (SpA). Electron microscopy of mouse spleen lymphocytes and thymocytes (previously coated with mouse IgG anti-Thy-1 antibody) treated with IgG anti-Fer/SpA/IgG anti-mouse Ig complex and Fer gave better resolution and higher accuracy than previously obtained with IgG anti-HRP/SpA/IgG anti-mouse Ig complex and HRP (Mandache et al., 1980). Surface Thy-1 alloantigen and Fc receptor (charged with human IgG) treated with a mixture of IgG anti-Fer/SpA/IgG anti-Thy-1 and IgG anti-HRP/SpA/IgG anti-human Fab could be simultaneously detected on the thymocyte surface by either light or electron microscopy using Fer and HRP. The concomitant visualization of Thy-1 alloantigen (with Fer) and FcR (with HRP) on mouse thymocyte clearly shows that their distribution is largely independent and that the amount of Thy-1 antigen is greater. These results show that electron microscopy with a mixture of MHA is a useful technique for simultaneous location of two antigenic markers on the cell surface.
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PMID:Simultaneous detection of two different cell surface antigens by electron microscopy by means of multivalent hybrid antibody with double specificity. 697 52

The interaction of ruminant IgG with human phagocytes was assessed using Fc receptor (FcR)-mediated ingestion and the triggering of a respiratory burst as effector functions indicative of receptor-specific interaction. In monomeric form, ruminant IgG was three to five orders of magnitude less potent than homologous IgG in inhibiting FcR-specific phagocytosis by monocytes. However, when attached to tanned sheep erythrocytes (Es-T), ruminant IgG was opsonic, as it promoted enhanced phagocytosis of Es-T, comparable to ingestion of rabbit IgG-coated Es. This phagocytosis was inhibitable by high concentrations of human IgG in the fluid phase. Moreover, Es-T precoated with ferritin could be opsonized to a similar degree by anti-ferritin IgG from rabbit and cow. However, only bovine IgG1, but not IgG2, was opsonic. Bovine and goat IgG of some, but not other, suppliers were inactive. Similar results were obtained by measuring the respiratory burst triggered by heat-aggregated IgG, using a luminol-enhanced chemiluminescence assay. Thus, human IgG and ruminant IgG stimulated monocytes and, to a lesser extent, polymorphonuclear leucocytes (PMN), to generate CL. Depending on the manufacturer, some preparations of bovine and goat IgG were inactive, and bovine IgG2 failed to induce CL. These findings prove that certain ruminant IgG preparations, including bovine IgG1 interacting weakly with homologous PMN and monocytes, do interact with human PMN, monocytes and macrophages in a FcR-specific manner when offered in complexed form. Inhibition studies suggest that bovine IgG1 interacts mainly with human FcR type II. In contrast, bovine IgG2, regarded as cytophilic for homologous PMN, fails to interact with human PMN, monocytes and macrophages.
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PMID:The interaction of ruminant IgG with receptor type II for IgG on human phagocytes. 1549 77


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