Analysis of immunoglobulin receptors during antigen-induced maturation of B cells.
Explore the source record for details and available documents.
Animals↗
SEARCH · PubMed Health
Results for “Immunologic Capping”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Hapten-sandwich labeling of cell-surface antigens.
Explore the source record for details and available documents.
Animals↗
Severe combined immunodeficiency with T lymphocytes retaining functional activity.
Two cases of severe combined immunodeficiency (SCID) with normal numbers of T cells are reported. Studies of T-cell subsets showed an absence of TQ1+ lymphocytes and a very low percentage of CD4+ cells in Patient 2. Functional studies of T cells from this patient showed a normal suppressor activity. Patient 1 had normal percentages of T-cell subsets and his lymphocytes showed helper and suppressor activities but to a lesser degree than normal controls. Both cases stressed the heterogeneity of SCID in which T cells could be present and retain some of their functional activities.
Antibodies, Monoclonal↗
The acquired immunodeficiency syndrome: an ultrastructural study.
Blood and a variety of tissues from 97 patients with the acquired immunodeficiency syndrome (AIDS) and 25 with the AIDS prodrome were studied ultrastructurally. Tubuloreticular structures (TRS) were found in 85 per cent of the patients with AIDS and in 92 per cent of those with the prodrome. Test tube and ring-shaped forms (TRF), found in 41 per cent of the patients with AIDS and in 8 per cent of those with the prodrome, increased with disease progression. Among the patients with AIDS, as the number of sites examined per case increased, the incidence of TRS and TRF tended to approach 100 per cent, suggesting that they are present in all patients with AIDS. Other changes seen frequently were immunologic capping of blood lymphocytes, intramitochondrial iron in blood reticulocytes and marrow normoblasts, megakaryocytic immaturity and platelet phagocytosis, collections of membranous rings in hepatocytic cytoplasm, suggestive of non-A, non-B hepatitis, and proliferations and engorgement of hepatic Ito cells with lipid. The data suggest that TRS and TRF can be used as diagnostic and prognostic markers.
Acquired Immunodeficiency Syndrome↗
Local aggregation of hormone-receptor complexes is required for activation by epidermal growth factor.
An analogue of epidermal growth factor (EGF) which is virtually devoid of biological activity retains receptor binding activity but cannot form cell surface clusters or patches. Bivalent anti-EGF antibodies restore both bioactivity and patch formation. The sensitivity of fibroblasts to native EGF can also be enhanced greatly by these antibodies, especially in hormone-resistant cell lines.
Animals↗
Treatment of murine CD5- B cells with anti-Ig, but not LPS, induces surface CD5: two B-cell activation pathways.
Anti-Ig stimulated murine B cells express high levels of surface CD5 (ly-1) and increased CD44 while maintaining surface IgD, CD23 and J11d. Sorting of CD5- and CD5+ cells demonstrates that anti-Ig induces CD5 expression rather than the selective expansion of CD5+ cells. Anti Ig plus interleukin-6 (IL-6) induces the CD23, IgD, low ly-5 (B220) (CD45low), J11dhigh phenotype of typical CD5+ peritoneal B cells. In contrast, lipopolysaccharide (LPS)-stimulated B cells have high levels of CD44 but decreased surface IgD, CD23 and J11d and no CD5. Thus LPS and anti-Ig generate activated cells with differing phenotypes. Induced CD5+ cells have increased viability, even in the absence of added exogenous factors, while the viability of CD5- B cells is dependent on factors such as IL-4. We conclude that conventional CD5- B cells can be activated by either of two pathways: one generating CD5+ B cells; the other yielding conventional activated cells. We hypothesize that the first path requires slg cross-linking and corresponds to T-independent (type 2) stimulation, while cognate interaction with helper T cells in the absence of slg cross-linking induces B cells to enter the second path.
Animals↗
Scanning immunoelectron microscopy for the identification and mapping of two or more antigens on cell surfaces.
This study demonstrates the feasibility of using scanning electron microscopy for the identification and mapping of two or more antigens on cell surfaces. Three types of cells: human type B red cells, tumor cells and their associated virus, and guinea pig hepatocarcinoma cells were immunolabeled with ferritin or gold conjugated to IgG fractions of antigen-specific antisera. Gold particles, 300-500 A in diameter, were conjugated to an IgG fraction either directly or indirectly using Staphylococcal protein A. Gold particles of this size can be distinguished from ferritin label using a high resolution scanning microscope. Correlative light, transmission electron microscopy, and scanning electron microscopy studies, as well as x-ray diffraction analysis and the study of stereo micrographs, were performed to visualize the simultaneous immunolabeling by ferritin and gold of two antigens on the guinea pig hepatocarcinoma cell.
Animals↗
[Function of neonatal neutrophilic granulocytes].
Phagocytic leukocytes especially neutrophils form an essential part of human host defense against infection by invading microorganisms. The principal activities exhibited by circulating neutrophils in response to inflammation include adherence to vascular endothelium, chemotaxis, phagocytosis and microbial killing. As reviewed in this article, each of these aspects of cell function has been studied in neutrophils of newborn and preterm infants. The most consistent finding has been abnormal chemotaxis. Whether the newborn infant who suffers from an increased susceptibility to serious infections is actually predisposed to infection because of deficiencies in neutrophil function remains questionable. It seems likely that subnormal phagocyte function combined with other defects in host defense such as deficient complement and opsonizing activity in neonatal sera could predispose the newborn infant to bacterial infections that rapidly become systemic.
Bacterial Infections↗
Imaging of immunogold labelled antigens on capping thymocytes by confocal reflection contrast scanning optical microscopy.
Confocal laser scanning optical microscopy (CLSM) in the reflection contrast mode has been used to image single 40 nm gold particles, and to study changes in the distribution of gold label associated with capping of the leukocyte sialoglycoprotein (LSGP) antigen on the surface of fixed rat thymocytes, labelled with the mouse monoclonal antibody W3/13 and a goat anti-mouse IgG immunogold conjugate. This imaging method has also been applied to live thymocytes labelled with gold-conjugated antibodies, to study the dynamics of the capping process.
Animals↗
[Immunological tolerance: induction and abrogation].
The induction of a state of immune tolerance is a complex event which can take place at different stages of the immune response since it depends both upon the chemical structure and the experimental manipulation of the antigen. This paper deals mainly with the relationship between antigen structure and the kinds of tolerance induced.
Animals↗
Receptor patching and capping of platelet membranes induced by monoclonal antibodies.
Redistribution of glycoproteins (GP) Ib, glycocalicin, IIb, and IIIa on the surface of human platelets in response to stimulation with corresponding monoclonal antibodies (MoAb) and a polyclonal antiglycocalicin antibody was studied by immunofluorescence, immunoelectron microscopy, and a quantitative radioimmune assay. Immobilization of the antigens by prefixation with formaldehyde showed a uniform distribution over the surface of the platelet. Incubation of unfixed platelets with specific MoAb against various epitopes on GPIIb and/or IIIa resulted in a time-dependent patching, subsequent capping, and after prolonged exposure to the antibody/label complex, internalization of the complex, possibly by endocytosis. In contrast, GPIb could not be shown to cap. From these results we conclude that platelet GPIIb and/or IIIa undergo spatial rearrangement in a manner analogous to that observed in lymphocytes, whereas GPIb does not. Since both GPIb and GPIIb and/or IIIa seem to be transmembraneous GP associated with the cytoskeleton, a special, though unidentified, role of GPIIb/IIIa in the induction of lateral membrane mobility is postulated.
Antibodies, Monoclonal↗
Moloney lymphoma cells express a polyprotein containing the GAG gene-coded p15 and the Moloney leukemia virus-induced cell surface antigen (MCSA).
The relationship between MCSA and the viral structural proteins in YAC Moloney lymphoma cells was further investigated by using membrane immunofluorescence and immunoadsorbent columns. As previously observed, MCSA showed only minimal capping and thereby differed in behaviour from gp70, p30 and p12 virion antigens. Whereas antibody-induced capping of gp70 did not change the membrane distribution of MCSA, co-capping was observed between MCSA and p30 and p12 gag protein antigens. This indicated that, whereas MCSA is distinct from gp70, it is linked to p30 and p12 on the membrane of living cells. It was then attempted to isolate MCSA on anti-p30 and anti-p15 immunoadsorbent columns from solubilized YAC cells. Contrary to what was expected, no MCSA was found to the anti-p30 column. On the other hand, a part (10-15%) of the MCSA was bound to the anti-p15 column, indicating that MCSA is linked to the gag p15.
Animals↗
Isoform-specific associations of CD45 with accessory molecules in human T lymphocytes.
Association of CD45 with surface molecules was investigated in human T lymphocytes by co-capping. CD45 appeared to be associated with the CD3/T cell receptor complex and with CD4 or CD8 molecules in memory, but not in naive T cells, as previously reported in the mouse. Associations of CD45 isoforms with accessory molecules were then identified with seven anti-CD45R monoclonal antibodies (mAb). An isoform-specific association pattern was observed: CD2 co-capped with CD45 molecules recognized by UCHL1 mAb (CD45R0). LFA-1 with molecules bound by 2H4 mAb (CD45RA), and both CD4 and CD8 with molecules reacting with MCA.347 mAb (whose isoform specificity was not known). Further information on the CD45 isoform(s) associated to CD4 and CD8 was sought by assessing the isoform specificity of MCA.347. Cross-competition experiments showed that it reacts with an epitope clearly different from those recognized by 2H4 and UCHL1, and only partially overlapping the PD7/26 epitope (CD45RB). Moreover, the competition between MCA.347 and PD7/26 was maximal in naive T cells and minimal both in memory T cells and in a subset expressing CD11b, a marker of granular lymphocytes. Immunoprecipitation experiments showed that MCA.347 binds to CD45 molecules with a molecular mass of 220, 205 and 190 kDa, the 190-kDa molecules not being recognized by 2H4, PD7/26 or UCHL1. These data indicate that MCA.347 recognizes amino acid sequences different from those coded by the exon A or B of the gene, and not expressed by CD45R0, suggesting that it binds to sequences coded by the exon C. In conclusion, this work shows that in human T cells different CD45 isoforms are associated to different surface molecules: LFA-1 is associated to CD45RA, CD2 to CD45R0 and CD4 and CD8 presumably to CD45RC. This peculiar behavior of CD45 suggests that it may play a crucial role in lymphocyte activation, probably by modulating the signals delivered to the cell by different receptor systems.
Antibodies, Monoclonal↗
Functional studies with anti-CD3 heavy chain isotype switch-variant monoclonal antibodies. Accessory cell-independent induction of interleukin 2 responsiveness in T cells by epsilon-anti-CD3.
A series of heavy chain isotype switch-variant anti-CD3 monoclonal antibodies (mAb) was used to study the proliferation requirements of purified T cells. None of the variant antibodies was able by itself to induce proliferation. In the presence of exogenous interleukin 2 (IL-2) strong mitogenesis was observed upon stimulation with epsilon-anti-CD3, whereas gamma 1, gamma 2b, gamma 2a, and alpha-anti-CD3 failed to induce T cell proliferation. All variant antibodies induced vigorous proliferation in combination with phorbol myristate acetate. Purified T cells, cultured in the presence of epsilon-anti-CD3, in the absence of IL-2, did not express detectable amounts of TAC-antigen (CD25). The binding of the variant antibodies to the CD3 antigen was evaluated in cross-blocking experiments. It was demonstrated that the epsilon-anti-CD3 antibody, in comparison with the other variant mAb, has a relatively low avidity for the CD3 antigen. In modulation experiments, the IgE variant antibody was unable to induce a substantial loss of CD3 antigen. T cell triggering was investigated at the level of Ca2+ mobilization by means of the dye Indo-1. In contrast to the gamma 1, gamma 2b, gamma 2a, and alpha mAb, which induced a rapid and high rise in the free intracellular calcium level, epsilon-anti-CD3 caused a slow and low rise. These studies indicate that the epsilon-anti-CD3 antibody has a low avidity for the CD3 antigen, compared with the other variant mAb, possibly as a result of monovalent binding. Apparently, the avidity and/or valency of CD3 antigen binding not only has a major influence on CD3 modulation and anti-CD3-induced Ca2+ mobilization, but also sets T cell requirements for IL-2 responsiveness.
Antibodies, Monoclonal↗
Lymphocyte capping in Duchenne muscular dystrophy.
Explore the source record for details and available documents.
Humans↗
Model for capping of membrane receptors based on boundary surface effects.
Crosslinking of membrane surface receptors may lead to their segregation into patches and then into a single large aggregate at one pole of the cell. This process is called capping. Here, a novel explanation of such a process is presented in which the membrane is viewed as a supersaturated solution of receptors in the lipid bilayer and the adjacent two aqueous layers. Without a crosslinking agent, a patch of receptors that is less than a certain size cannot stay in equilibrium with the solution and thus should dissolve. Patches greater than a certain size are stable and can, in principle, grow by the precipitation of the remaining dissolved receptors from the supersaturated solution. The task of the crosslinking molecules is to form such stable patches. These considerations are based on a qualitative thermodynamic calculation that takes into account the existence of a boundary tension in a patch (in analogy to the surface tension of a droplet). Thermodynamically, these systems should cap spontaneously after the patches have reached a certain size. But, in practice, such a process can be very slow. A suspension of patches may stay practically stable. The ways in which a cell may abolish this metastable equilibrium and thus achieve capping are considered and possible effects of capping inhibitors are discussed.
Cell Membrane↗
Compound receptors in the cell membrane: ruminations from the borderland of immunology and physiology.
Explore the source record for details and available documents.
Antibodies, Monoclonal↗
The role of caldesmon in the regulation of receptor capping in mouse T-lymphoma cell.
Several complementary techniques, including immunocytochemical and immunobiochemical analyses, two-dimensional gel electrophoresis, and peptide mapping, were used in this study to examine the involvement of caldesmon in lymphocyte receptor capping. We have found a lymphoma 140-kDa polypeptide that is structurally similar to muscle caldesmon, suggesting that this polypeptide may be a lymphoma caldesmon. When lymphoma 140-kDa polypeptide is extracted from permeabilized cells using 25 mM MgCl2, capping is inhibited. Adding the 140-kDa protein or gizzard caldesmon back to the extracted cells restores their ability to cap. These findings suggest that actin-linked regulatory proteins such as caldesmon may be critically important to actomyosin-mediated contraction which, in turn, is responsible for collecting receptors into cap structures.
Animals↗