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Results for “Immunologic Capping”

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At least 19 recordsLinked to original sources
PubMed1984

Differences in capping behavior between immunological phenotypes in childhood acute lymphoblastic leukemia. A study with ConA and an anti-HLA-ABC backbone.

Capping with concanavalin A (ConA) and monoclonal anti-HLA-ABC backbone was studied in childhood acute lymphoblastic leukemia (ALL). Capping with ConA and HLA gave quite different results, both in common ALL and T-ALL. With ConA most cases capped poorly, comparable to results described in chronic lymphatic leukemia and lymphoma, but in several cases capping was comparable to that of normal lymphocytes. In HLA capping T-ALL cells capped better than common ALL cells. HLA capping of T-ALL cells is comparable to that of normal lymphocytes. HLA capping results in handmirror cell formation giving support to the hypothesis that capping and motility are associated events.

Antibodies, Monoclonal↗
PubMed1995

Expression and function of the murine CD95/FasR/APO-1 receptor in relation to B cell ontogeny.

Mice defective in Fas-mediated apoptosis (lpr phenotype) have an intrinsic B cell abnormality that predisposes them to autoantibody production. To investigate potential roles for the Fas receptor (FasR) in B cell tolerance, FasR expression and function were evaluated at different stages of B cell development. FasR expression was very low or absent on pro- and pre-B cells, but was detected in early B cell lines and was up-regulated following IFN-gamma-induced maturation of the pre-B cell line 70-Z. Whereas FasR expression was very low in resting mature sIgM+ B cells, expression was markedly increased following mitogen activation and was also elevated in two mature sIgG+ lymphoma lines. FasR expression correlated strongly with the ability of B cells to undergo Fas-mediated apoptosis. In addition, although Fas did not appear to play a direct role in apoptosis mediated by cross-linking of sIg with anti-IgM, anti-FasR and sublethal concentrations of anti-Ig were additive in the induction of apoptosis in the early B cell line WEHI 231. These findings suggest that the Fas pathway is not involved in the elimination of pro- and pre-B cells, but are compatible with an ancillary role for FasR in the elimination of early B cells and elimination of mature B cells following activation.

Animals↗
PubMed1996

CD9 of mouse brain is implicated in neurite outgrowth and cell migration in vitro and is associated with the alpha 6/beta 1 integrin and the neural adhesion molecule L1.

We describe here a novel monoclonal antibody (mab H6) which recognizes CD9, an integral cell surface constituent previously described in cells of the hematopoietic lineage and involved in the aggregation of platelets. Mab H6 was raised against membranes of immature mouse astrocytes and reacted with a protein of 25-27 kD in detergent extracts of adult mouse brain membranes. Sequence analysis of the N-terminal amino acids revealed an identity of 96% with CD9 from mouse kidney. CD9 was localized in the central and peripheral mouse nervous systems: in the spinal cord of 11-day-old mouse embryos, CD9 was strongly expressed in the floor and roof plates. In the adult mouse sciatic nerve, myelin sheaths were highly CD9-immunoreactive. Mab H6 reacted with the cell surfaces of both glial cells and neurons in culture and inhibited migration of neuronal cell bodies, neurite fasciculation and outgrowth of astrocytic processes from cerebellar microexplants. Neurite outgrowth from isolated small cerebellar neurons was increased in the presence of mab H6 on substrate-coated laminin, but not on substrate-coated poly-L-lysine. Addition of mab H6 elicited an increase in intracellular Ca2+ concentration in these cells on substrate-coated laminin. Immunoprecipitates of CD9 from cultured mouse neuroblastoma N2A cells contained the alpha 6/beta 1 integrin. Moreover, preparations of CD9 immunoaffinity-purified from adult mouse brain using a mab H6 column contained the neural adhesion molecule L1, but not other neural adhesion molecules. CD9 bound to L1, but not to NCAM or MAG. Both the alpha 6/beta 1 integrin and L1 could be induced to coredistribute with CD9 on the surface of cultured neuroblastoma N2A cells. The combined observations suggest that CD9 can associate with L1 and alpha 6/beta 1 integrin to influence neural cell interactions in vitro.

Amino Acid Sequence↗
PubMed1995

Activation of B-cells by sIgM cross-linking induces accumulation of CD5 mRNA.

The surface membrane molecule CD5 is expressed on mature T cells and on the B-1a subpopulation of B cells. These CD5 positive B cells express an antibody repertoire with a relatively high frequency of self-reactivity. There is uncertainty about the origins of CD5 B cells and the reasons for this are reviewed. Recent reports which relate to the lineage/selection debate are discussed. For instance, an increase in the frequency of CD5 B cells is a feature of several genetically determined polysystem autoimmune syndromes. In the case of motheaten (me, mev) the pathogenesis of this increase in CD5 B cells is not yet understood, even though the mutation has been mapped to the Hematopoietic cell protein-tyrosine phosphatase (Hcph) gene. Another mutation which affects B cell development, X-linked immunodeficiency (xid), encodes a point mutation in a B cell cytoplasmic tyrosine kinase. Expression of xid in otherwise normal mice causes a lack of CD5 B cells and a shift in the antibody repertoire. Interestingly, expression of both xid and motheaten results in an amelioration of autoantibody production. Evidence is presented that in B cells regulation of expression of CD5 can occur at the level of mRNA and that cross-linking of sIgM can induce the accumulation of CD5 mRNA. The overall concept advanced is that cells expressing natural autoantibodies are triggered via sIgM ligation to become CD5 B cells.

Animals↗
PubMed1988

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↗
PubMed1985

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↗
PubMed1979

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↗
PubMed1996

Concurrent engagement of CD40 and the antigen receptor protects naive and memory human B cells from APO-1/Fas-mediated apoptosis.

Naive and memory B cells were isolated from human tonsils and examined for expression of APO-1/Fas and for their sensitivity to the APO-1-dependent apoptosis. APO-1 was found to be constitutively expressed on memory but not on naive B cells. The susceptibility of both cell types to the APO-1 apoptotic pathway was acquired upon CD40 triggering and was correlated with increased expression of the APO-1 receptor. Both naive and memory B cells were protected from the APO-1-mediated death signal after dual ligation of the Ag receptor adn CD40. Our findings suggest that the APO-1 pathway controls the specificity of B cell responses to T-dependent Ags and that occupancy of the Ag receptor dictates the outcome of APO-1-ligation on B cell survival.

Antigens, CD↗
PubMed1996

GlyCAM-1, a physiologic ligand for L-selectin, activates beta 2 integrins on naive peripheral lymphocytes.

Naive T cells are selectively recruited from the blood into peripheral lymph nodes during lymphocyte recirculation. L-selectin, a lectin-like receptor, mediates the initial attachment of lymphocytes to high endothelial venules (HEV) in lymph nodes. A subsequent step involving the activation of beta 2 integrins has been proposed to facilitate firm adhesion, but the activating signals are poorly understood. We report here that either antibody-mediated cross-linking of L-selectin on human lymphocytes or treatment of the cells with GlyCAM-1, an HEV-derived, secreted ligand for L-selectin, stimulates their binding to ICAM-1 through the beta 2 integrin pathway. Furthermore, GlyCAM-1 causes the rapid expression of a neoepitope on beta 2 integrins associated with a high-avidity state. Naive (CD45RA+), but not memory (CD45R0+) lymphocytes, respond to L-selectin cross-linking or GlyCAM-1 treatment. Thus, the complexing of L-selectin by specific ligands may provide key signals to naive lymphocytes, contributing to their selective recruitment into peripheral lymphoid organs.

Antibodies, Monoclonal↗
PubMed1991

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↗
PubMed1979

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↗
PubMed1985

[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↗
PubMed1983

Surface and cytoskeletal events regulating leukocyte membrane topography.

The experiments reviewed here establish that surface components and surface functions can assume predictable, asymmetric patterns within the continuous plasma membranes of mammalian leukocytes. Recent biophysical and morphological studies show that receptor redistribution can occur very rapidly and that a unique geometric association is maintained between moving receptors and surface geometry. Based on these experimental data, a new working model for surface topographical control has been proposed. Its essence is the entrainment of certain receptors and receptor complexes on membrane waves that are generated by microfilament-membrane interaction. Several pathological conditions associated directly or indirectly with cytoskeleton and membrane abnormalities have been described. The continued application of modern biochemical, immunologic, and biophysical techniques to probe the underlying defects should provide new insight into the mechanisms of leukocyte response to surface stimulation.

Cell Membrane↗
PubMed1981

Immunocytochemical localization of intermediate filament proteins during lymphocyte capping.

Using double immuno-fluorescence techniques on frozen-thick sections, we have examined the fate of intermediate filaments during Con A receptor capping in lymphoid cells. Our results indicate that during capping intermediate filaments are preferentially aggregated between the surface receptor cap structure and the cell nucleus. It is possible, therefore, that intermediate filaments are directly involved in lymphocyte capping.

Animals↗