摘要:

SummaryPeroxidase‐conjugated anti‐surface immunoglobulin (slg) was used quantitatively to monitor endocytosis of crosslinked sIg on murine B lymphocytes. The role of biochemical second messengers in the initiation of endocytosis was assessed by employing several inhibitors. A novel peroxidase detection system was used and temperature‐dependent decreases in sIg density on immunoperoxidase‐labelled murine lymphocytes were monitored. Metabolic inhibitors as well as colchicine and cytochalasin D were utilized to confirm that the internalization of sIg could be blocked by classical inhibitors of the endocytosis process. The role of tyrosine kinase activity was established by the fact that endocytosis was significantly reduced with 100 μg/mL genistein. Experiments using EGTA or 1,2‐bis(β‐aminophenoxy)ethane‐N‐N,N′‐tetraacetic acid (BAPTA) to chelate Ca2+indicated that Ca2+plays little role m endocytosis. Likewise, protein kinase C (PKC) was not found to be involved in endocytosis, as activation of PKC with 50 ng/mL phorbol 12‐myristate 13‐acetate, or inhibition of the enzyme with 1 nmol/L or 5 nmol/L staurosporin, did not modulate endocytosis. Taken together, results suggested that ligand‐induced endocytosis of antigen receptors is mediated primarily through localized membrane events and is not dependent upon the classical B lymphocyte activation signals, such as the biochemical events in the inositol phosphate cascade.

ISSN:0004-945X    

DOI:10.1038/icb.1993.1

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

摘要:

SummaryThe antibody response of mice and adult humans to immunization with subunit vaccines derived from a pair of antigenically distinct influenza A H1N1 viruses isolated in eggs was investigated. Although the haemagglutination molecule of each virus differed by only three amino acid residues, highly specific antibody responses were elicited in mice as determined by haemagglutination inhibition and radioimmunoprecipitation assays. Results from competitive radioimmunoassays using monoclonal antibodies of known specificity and a study of the reactivity of mouse antisera with H1N1 field strains indicated that the marked differences in the antibody responses to the two vaccines was due to an amino acid substitution in the distal tip of the haemagglutinin molecule. In contrast, crossreactive antibody responses were elicited in humans presumably due to exposure to viruses related to the candidate vaccine prior to vaccination. Although immunogenic differences are apparent in this pair of antigenically distinct viruses in naive laboratory animals, these differences are not apparent following vaccination of humans that had prior exposure to related viruses.

ISSN:0004-945X    

DOI:10.1038/icb.1993.2

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

摘要:

Summaryγδ T cells are capable of mediating non‐major histocompatibility complex (MHC) restricted lysis of a variety of tumour cell lines. The mechanism of this lysis and its significance in tumour immunity are not clear. We have used a panel of five malignant mesothelioma (MM) cell lines, as well as standard tumour targets K562 and Daudi, to investigate some of the factors which could be involved in non‐MHC restricted cytotoxicity mediated by γδ T cells. Individual MM ceil lines, representing a panel of lines derived from a single cell type, varied in their susceptibility to lysis by γδ T cell clones. Individual γδ T cell clones also showed unique cytotoxic profiles, and differed in their cytotoxic potential. T cell receptor (TCR) γδ gene usage correlated with the ability of clones to lyse Daudi or K562; clones lysing Daudi expressing Vγ9 and clones lysing K562 expressing VγI subgroup genes. No strict correlation between Vγ and Vδ gene usage and MM reactivity was, however, demonstrable. There was also no correlation between yδ T cell lysis of MM cell lines and the capacity of γδ T cells to produce interferon‐γ, tumour necrosis factor‐α, interleukin‐2 or interleukin‐4, nor with their expression of CD8.

ISSN:0004-945X    

DOI:10.1038/icb.1993.3

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

摘要:

SummaryMultiple levels of regulation of collagenase (matrix metalloproteinase 1; MMP‐1), have been demonstrated in a clonal rat epithelial cell line (A5P/B10). Secreted enzyme could not be demonstrated in culture medium from A5P/B10 cells but, using antibodies specific for collagenase, the enzyme was detected within the cytoplasm and on the surface of the cells. A probe for rat collagenase could not detect a signal for mRNA in the cytoplasm while nuclear run‐on data demonstrated that the gene for collagenase was being transcribed. Incubating the cells with 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) significantly increased cytoplasmic mRNA levels and slightly increased the intensity of staining in permeabilized cells, but collagenase activity was still not detected in the conditioned medium. This indicated that the protein was being synthesized by the TPA‐treated cells but was not being secreted into the medium. These data suggest that the secretion of collagenase may be regulated both following transcription and after the completion of translation and it is suggested that multiple levels of control may be operating to determine the rate of collagenase release and hence, the rate of collagen turnover.

ISSN:0004-945X    

DOI:10.1038/icb.1993.4

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

摘要:

SummaryThe trophoblast, an epithelial cell of fetal origin that forms the physical barrier between the mother and developing conceptus, becomes a component of the host immune system during pregnancy. Of the classical immune cells, it most closely resembles the macrophage, also present in high numbers in the pregnant uterus. The macrophage and trophoblast, as cell classes, share characteristics such as phagocytosis, syncytialization, invasiveness, expression of the proteins CD4, CD14, IgG receptor (FcR), non‐specific esterase, granulocyte macrophage‐CSF (GM‐CSF), Colony stimulating factor 1 (CSF‐l), interleukin‐I (IL‐1), interleukin‐6 (IL‐6), tumour necrosis factor (TNF‐α), transforming growth factors (TGF), platelet‐α derived growth factor (PDGF) and receptors for these cytokines. In the uterus both cell types appear regulated by a common element, the uterine epithelium, that secretes cytokines such as CSF‐1, GM‐CSF, TNFα, TGFβ, IL‐6, and leukaemia inhibitory factor (LIF) that target both macrophages and trophoblasts. The common characteristics and regulation that make teleological sense in terms of co‐ordinating local uterine immunity during pregnancy may also be important in transmission of congenital diseases such as AIDS. The production by the uterine epithelium of a number of cytokines previously only associated with mononuclear phagocyte production and function predicts the existence of a similar, but broader, shared cytokine network encompassing trophoblast and the principal immune regulatory cell, the T lymphocyte.

ISSN:0004-945X    

DOI:10.1038/icb.1993.5

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

摘要:

SummaryCD45 isoform transitions appear to play essential roles in both life and death, and correlate with the stages of thymocyte development during which there is a change in physical location from medullary and/or outer cortical areas to the inner cortex. This work speculates that CD45 isoforms, through a focal role in the assembly of adhesive complexes mediated by the external domains, participate in the maintenance and/or modulation of migratory behaviour by differentiating thymocytes, or alternatively in the anchoring of thymocytes in a generative micro‐environment. The objective of the sections that follow is to formulate the hypothesis that CD45 isoforms, through their differential interactions with adhesion molecules expressed by T cells, profoundly influence cell motility and consequent micro‐environmental localization. An adhesive assembly of CD45 and adhesion molecules on the outside, and of the adhesive complex with the cytoskeleton on the inside, would promote CD45‐mediated regulation of adhesion/de‐adhesion through lateral external interactions mediated by external domains of CD45 isoforms, through enzymatic modulation of the cytoplasmic domains of adhesion molecules by the CD45 tyrosine phosphatase activity, and through phosphatase control of cytoskeletal assembly and disassembly.

ISSN:0004-945X    

DOI:10.1038/icb.1993.6

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY

摘要:

SummaryAdult worms ofStrongyloides ratti, after elimination from the small intestine, were retained in the caecum for at least three days during the infection in mice. This retention was a biological event but not due to a simple mechanical trapping in faeces. In addition to the local mucosal mastocytosis, eosinophil infiltration was remarkable in the caecum around day 10 when adult worms were expelled from there.

ISSN:0004-945X    

DOI:10.1038/icb.1993.7

出版商:Blackwell Publishing Ltd    

年代:2017

数据来源: WILEY