摘要:

Tlymphocytes express multiple forms of the leukocyte‐common antigen CD45, transcribed by alternative usage of leukocyte‐common antigen exon 4 6. The various isoforms of CD45R expressed differentially on T cells are involved in different stages of development and activation. The monoclonal antibody (MoAb) RA3‐6B2 is established as a B cell‐type isoform (B220)‐specific marker. However, it reacts with certain activated T cells although the relationship between 6B2 expression and T‐cell activation is unclear. We have examined the 6B2 expression on activated T cells and found that concanavalin A, anti‐CD3 antibody and staphylococcal enterotoxin B (SEB) induced 6B2 expression on T cells. The expression was found on both CD4+and CD8+T cells and also was induced by SEBin vivopredominantly on CD8+T cells. The 6B2+T cells are IL‐2R+and blasted cells according to flow cytometry analysis. Therefore, the 6B2+T cells are supposed to be in an activated stage. Enzymatic analysis demonstrated that trypsin treatment decreased the 6B2 expression, whereas neuraminidase increased the intensity on activated T cells. Neither endo‐D or endo‐H have any effect on the expression and there are no differences, in the results of immunoprecipitation and RT‐PCR analysis, between control T cells and activated T celts. Taken together, the 6B2 epitope is presumed to be the product of CD45R modification and is expressed on activated T cells. These results illustrate a novel classification of a T‐cell subpopuiatio

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03395.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Hereditary haemochromatosis (HH) is an autosomal recessive disease linked to certain MHC class‐I specificities. The disease is characterized by increased iron absorption and, in some patients, abnormally low numbers of CDS8+T cells in the periphery. We were interested in whether CD4‐ and CD8‐associated p561ck kinase activities were altered in patients with HH. In a study of 18 patients with HH (with and without low numbers of CD8+cells), the level of autophosphorylation of the CD8‐associated p561ck as well as its phosphotransferase activity, as determined by phosphorylation of an exogenous substrate, was significantly reduced by two‐ to three‐fold relative to a control population of 23 healthy blood donors (P<6 × 10−7). CD8‐p56 lck activity was decreased in 16 out of 18 patients (ranging from 1.5‐ to 10‐fold decrease). By contrast, the level of CD4‐p561ck activity did not show an overall decrease relative to controls. In addition to an occasional decrease in the amount of CD8‐associated lck, HH patient‐derived T cells showed a consistent decrease in the relative CD8‐p561ck specific activity. Immunofiuorescence staining showed further that the difference could not be accounted by a discrepancy in the expression of CD8αα or CD8αβ complexes or MHC class I molecules. Decreased CD8‐p561ck activity was seen both in patients undergoing intensive phlebotomy treatment and in patients in maintenance therapy (i. e. patients who had reached normal levels of iron stores), indicating that this abnormality does not appear to be corrected by iron depletion. To our knowledge, this is the first demonstration of an abnormality in a src‐like receptor associated kinase in a human disease

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03396.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

CD22 is a B cell lineage restricted cell‐surface adhesion glycoprotein which recognizes ligands on human T and B cells and cell lines. A soluble recombinant form of human CD22 (hCD22Rg) has been used to identify and characterize CD22‐specific ligands on human T cells, one of which has been shown to be the receptor‐linked phosphotyrosine phosphatase CD45. Because CD45 plays a pivotal role in lymphocyte activation, we assessed whether human CD22 might display cross‐species reactivity with CD45. In the study presented here we demonstrate that human CD22Rg recognizes several murine cell‐surface sialoglycoproteins. including CD45, containing sialic acid in a2, 6 linkage. Furthermore, hCD22Rg recognizes different ligands on functionally distinct T helper‐cell subpopulations and selectively binds medullary thymocytesin rivo. Our results confirm and extend previous observations that CD22 is a sialic acid‐binding lectin which interacts with CD45 and other glycoproteins capable of presenting α2, 6‐linked sialic acid in a manner that promotes high affinity binding. The cross‐species reactivity ofCD22 with its ligands underscores the potential physiologic importance ofCD22‐mediated lym

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03397.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

A broad range of plant lectins have recently been shown to inhibit the infectivity of herpes simplex virus type I (HSV‐1)in viiro. We decided to investigate the role of mammalian Icctins in infection witb herpes simplex virus. Two lectins, conglutinin and mannan‐binding protein (also called mannose‐binding protein. MBP). belonging to the collectin family of lectins, were examined.Four week‐old BALB/c mice were injected subcutaneously with 100 μg bovine conglutinin or 50 μg human MBP 1 day before intravenous infection with 5 × 104PFU of herpes simplex virus type 2 (HSV‐2). A three‐fold increase in virus titre of the liver was observed on day 3 of the infection in the mice pretreated with conglutinin or MBP. whereas no effect was seen on days I and 5.In a standard plaque assay using Vero cells we were not able to demonstrate reproducibly either infection inhibition or infection enhancement, when virus was pre‐incubated with differing concentrations ofthe collectins. Tbe concentrations used were similar to tbose used by usin livo, and by others inin vitroexperiments showing inhibition of the infectivity of HSV‐1 with plant lectins.In an ELISA with HSV‐2 antigens captured on anti‐HSV‐2 antibodies, calcium‐dependent and carbohydrate inhibitabte binding of the collectins was observed. Our results indicate that the effect of endogenous mammalian collectins in vivo may not be neutralization as suggested by the data using plant lectins. Instead, the previously described opsonizing activity of the mammalian collectins may provide the virions witb an alternative port of entry into cells leadin

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03398.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

(NZB X NZW)FI (B/W) mice spontaneously develop a disease which is remarkably similar to systemic lupus erythematosus (SLE) in humans. This disease is characterized by the appearance of autoantibodies to double‐stranded (ds)DNA and the subsequent development of fatal glomerulonephritis. The prophylactic treatment of B/W mice with syngeneic photomodulated autoimmune spleen cells was found to significantly improve survival, and to inhibit the outgrowth of autoreactive B cells and the production of high‐titre IgG anti‐dsDN A antibodies. The function of the autoreactive T cellsin vitro, however, did not change significantly. Our findings suggested a novel treatment for spontaneously occurring autoanti‐body‐rciated autoimmune

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03399.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Binding characteristics of a monovalenl bispecific monoclonal antibody (bsMoAb), which recognizes both epidermal growth factor receptor (EGF‐R) and drug doxorubicin (DXR) were compared with those of the parental bivalent MoAb directed against the EGF‐R binding site. Scatchard analysis indicated that both MoAbs bound to EGF‐R‐overexpressing A431 cells with the same affinity. In tracer amounts, both MoAbs also displayed the same capacity to be internalized after binding to the cell surface. However, when the MoAbs were used at saturating concentrations, down‐modulation of the receptor was greater with the bivalent MoAb. The bivalent MoAb also inhibited proliferation of A431 cells bothin vitroandin vivowhereas the bsMoAb was inhibitory only in vivo. These data suggest that MoAb bivalency is required for EGF‐R down‐modulation andin vitrocell grow

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03400.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The new monoclonal antibodies (MoAbs) E401, E811, E907 and E919 were prepared and characterized. These recognized an extracellular domain (amino acids No. 292–370) on the human c‐erbB‐2 gene product. Utilizing MoAb E811 and MoAb E919, a double determinant immunoassay (DDIA) was established to detect the soluble and the shed forms of the c‐erbB‐2 molecule. The levels of circulating erbB‐2 antigen in the sera of patients with benign diseases and healthy controls were very low. The incidence of positivity for shed c‐erbB‐2 antigen in gastric cancer, eolonic cancer, gall‐bladder caneer, pancreatic eancer and other cancers were 7.4%, 4.2%, 0%, 6.7% and 0%, respectively. Four of 54 patients with gastric carcinoma showed high levels of serum c‐erbB‐2 antigen. They belonged to clinical stage IV and their histological types were all well differentiated adenoeareinomas (two papillary and two tubular adenoeareinomas). Furthermore, the incidence of positive staining in gastric cancer was 34.6%; higher than that for shedding erbB‐2 antigen. Most of the cases v‐hich showed erbB‐2 expression on cells were well‐differentiated adenoeareinomas. Meanwhile, the distribution of erbB‐2 antigen was limited in normal tissues. The results suggest that the expression of erbB‐2 antigen is largely restricted to adenocarcinoma cells. It may not shed easily from these cells, and therefore It may be a very useful target m

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03401.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Virus‐specific cytotoxic T cells recognize antigens in the form of peptides (8 or 9 amino acids long) bound to MHC class‐I molecules. Exposure of unprimed murine splenocytes to synthetic peptides of viral antigens elicits primary CTL in vitro. The fme specificity of such CTL as well as the correlation between binding affinity of peptides to class‐I molecules and CTL induction was analysed using synthetic peptides corresponding to overlapping and distinct amino‐acid residues in SV40 T antigen (Tag) Db‐restricted T‐cell epitopes I, II‐III, and V. The peptides induced cross‐reactive CD8+primary CTL in spienocytes of naive C57 BL/6 mice. This reactivity was seen regardless of the peptides allelic anchor motifs or their abilities to stabilize empty class‐I molecules. However, none of the primary CTL and CTL lines lysed Tag‐expressing cells. In contrast, CTL generated in vivo by immunizing mice with Tag‐expressing cells recognized endogenously processed Tag as well as synthetic peptides. The peptides recognized by these CTL depended on the intracellular concentration of Tag antigen in the immunizing cells. The reactivity of these CTL was peptide specific as shown by a functional peptide competition assay. Moreover, three peptides bound to and were recognized in the context of both Kband Dbmolecules. These results have revealed a flexible disposition of MHC class‐I molecules with regard to peptide binding and also reflected lack of correlation between binding affinity to class‐1 molecules and the capacity of peptides to induce primary CTL or to serve as potential targets. The significance of these findings in relation to identifying major T‐cell epitopes using allele specific peptide motif and in vitro maintai

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03402.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The environmental pollutant 3, 3′, 4, 4′‐tetrachlorobiphenyl (TCB) leads to thymic atrophy and immuno‐suppression, the former possibly causing the latter. TCB binds lo the cytosolic aryl‐hydrocarbon receptor (AhR) and transforms it into a DNA‐binding state. The development of fetal thymocyles is severely affected by TCB and other AhR‐binding xenobiotics, leading to a skewed pattern of thymocyte maturation stages. Murine thymocyte proliferation after exposure to TCB was studied in fetal thymus organ culture (FTOC). C57BL/6 fetus thymic lobes from day 15 of gestation were explanted and grown for 2, 4, 6. and 8 days in organ culture in the presence or absence of 3.3 μM TCB. Subsets of thymocytes were defined by CD4 and CD8 surface markers, and their cell cycle was analysed by DNA staining with 7‐amino‐actinomycin D (7‐AAD). Exposure of fetal thymiin vitroto 3.3 μM TCB significantly reduced the total number of thymocytes. and fewer thymocytes were in S/G2M phase. The inhibition of cell proliferation induced by TCB treatment affected mainly the CD4−CD8−(double‐negative, DN) and CD4−CD8+(single‐positive, SP) subsets, and these inhibition appeared mainly in more immature thymocytes, i. e. DNCD3−and CD8+CD3−subpopulations, whereas no effect of TCB on CD4+CD8+(double‐positive, DP) cell proliferative activity was observed. Analysis of the relation of cell proliferation and development of subsets in differentiating fetal ihymocytes suggests that TCB enhanced thymocyte

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03403.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The cell line HMC‐1, derived from a patient with mast cell leukaemia, is the only established cell line exhibiting a phenotype similar to that of human mast cells. This paper reports on a detailed characterization of the expression of a panel of markers for various types of immature and mature haematopoietic cells in the HMC‐1. We also studied the potential of HMC‐1 to differentiate upon treatment with conditioned media from the human T‐cell line Mo, retinoic acid or DMSO.HMC‐1 was found to express several mast cell‐related markers. A high expression of Kit, the receptor for stem‐cell factor, was detected. The majority of the cells were stained with a MoAb against the mast cell‐specific serine protease tryptase. Of particular interest was the finding that β‐tryptase mRNA, but not a‐tryptase mRNA, was expressed in HMC‐1. Using enzyme‐histochemistry we were able to show that the β‐tryptase was enzymatically active, indicating that tryptase can form active homotetramers. Both heparin and chondroitin sulfate were found to be present in approximately equal amounts. HMC‐1 lacked surface expression of the high‐affinity IgE receptor, which was confirmed by the absence of mRNA of the α‐ and β‐chains of the IgE‐receptor complex. However, a strong expression of the 7‐chain of the IgE‐receptor complex was detected. A positive staining of the monocyte/macrophage marker CD68 was obtained, as well as a strong hybridization signal for the eosinophilic/basophilic‐related differentiation marker the Charcot‐Leyden crystal. Treatment of HMC‐1 with conditioned media from the human T‐cell line Mo, retinoic acid or DMSO induced only moderate changes in the surface or intracellular expression of the studied markers. The agents tested neither induced any of the monocyte/ granulocyte m

ISSN:0300-9475    

DOI:10.1111/j.1365-3083.1994.tb03404.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY