bluuebunny/crossref_metadata_2025_split huggingface dataset:
T cell activation by anti‐CD3 antibodies: function of Fc receptors on B cell blasts, but not resting B cells, and CD18 on the responding T cells
Authors: Austyn Jonathan M. , Smith Kenneth G. C. , Morris Peter J. 
Published: March 2007

AbstractMouse anti‐human CD3 (T3) antibodies can induce T cell proliferation in the presence of Fc receptor (FcR)‐bearing accessory cells. Depending on whether the particular antibody can interact with the FcR, it can be mitogenic or otherwise. Previously, some of us (Smith, K. G. C. et al., Eur. J. Immunol. 1986. 16: 478) examined human T cell responses to the murine anti‐CD3 antibody switch variants UCHT1 (IgG1) and UCHT1B (IgG2b). Using a novel xenogeneic system with mouse macrophages (MΦ) and an anti‐FcR antibody, 2.4G2, we obtained direct evidence for accessory function of FcR in these responses. However, mouse B cells which also possess FcR were not accessory cells.Here we show that resting B cells do not inhibit anti‐CD3 responses in the presence of other accessory cells, and they do not synergize with them. They appear to be inert in these responses but this is not simply because of their radiosensitivity. In contrast, B cell blasts proved to be potent stimulators of responses with UCHT1, UCHT1B and OKT3 (IgG2a). All three responses were inhibited by 2.4G2, whereas we have shown previously that the OKT3 response with MΦ was not, in keeping with the known specificities of B cell and MΦ FcR. These findings are discussed in relation to the molecular cloning of FcR, and we consider the possibility that distinct FcR could be expressed on resting and activated B cells.A report that anti‐CD18 (LFA‐1) antibodies blocked the UCHT1 response with human monocytes raised the possibility that this molecule might also be involved in accessory function. However, we show that this inhibition is in fact at the level of the T cell, since anti‐human, but not anti‐mouse CD 18 antibodies, inhibited proliferative responses and clustering with both human and mouse accessory cells. Our results demonstrate that the principal contribution of accessory cells to anti‐CD3 responses may be the provision of an FcR, and that CD18 is most probably required at the level of the T cell.
Regulation of the antibody response to sheep erythrocytes by monoclonal IgG antibodies
Authors: Quintana Ilana Zalcberg , Silveira Angela V. , Möller Güran 
Published: March 2007

AbstractMonoclonal antibodies directed against sheep erythrocytes of the isotypes IgG1,IgG2b and IgG2a were used to analyze the specificity of antibody‐induced suppression of the immune response. It was first shown that all monoclonals reacted against different antigenic determinants and they all suppressed the immune response to sheep erythrocytes when given shortly after the antigen to more than 50% as compared to 90–96% inhibition obtained with a polyclonal antiserum. Increasing the doses of monoclonals did not increase suppression. However, two different monoclonals administered together caused an additive, but not a synergistic inhibitory effect. No enhancement of the immune response was observed with any of the Ig classes tested. These findings show that four different antigenic determinants on sheep erythrocytes induced the synthesis of corresponding antibodies, with little or no signs of a dominant determinant. Passively administered monoclonal antibodies, even at supraoptimal doses, never suppressed the immune response to the same extent as a polyclonal antiserum, suggesting that each monoclonal only suppressed the synthesis of the corresponding antibody and did not affect antibody synthesis to other determinants.
Endothelial cell lysis induced by lymphokine‐activated human peripheral blood mononuclear cells
Authors: Miltenburg André M. M. , Meijer‐Paape Marion E. , Daha Mohamed R. , Paul Leendert C. 
Published: March 2007

AbstractIn vitro exposure of human peripheral blood mononuclear cells (PBMC) to interleukin 2 results in the generation of lymphokine‐activated killer (LAK) cells. Such LAK cells exhibit cytotoxicity against a spectrum of tumor target cell lines whereas they apparently do not affect normal tissues. In this report we show that PBMC that have been activated with T cell growth factor lyse trypsinized human umbilical cord venous endothelial cells as well as endothelial cell monolayers in a dose‐dependent manner. Microscopic analysis showed that during the 4‐h incubation period cell clumps containing detached endothelial cells and LAK cells were formed. When these clumps were evaluated with trypan blue the endothelial cells stained positive whereas LAK cells excluded the dye. No lysis occurred when fresh PBMC were added to target endothelial cells. The endothelial cell kill could not be blocked with an anti‐LFA‐1 antibody nor with intact OKT3 or F(ab′)2 fragments of WT32. We conclude that lymphokine‐activated PBMC exhibit cell‐mediated endothelial cell detachment and lysis.
Identification of a novel 45‐kDa cell surface molecule involved in activation of the human Jurkat T cell line
Authors: Carrel Stefan , Isler Patrick , Salvi Suzanne , Giuffrè Laura , Pantaleo Giuseppe , Mach Jean‐Pierre , Cerottini Jean‐Charles 
Published: March 2007

AbstractThis report describes a surface molecule, Tp45, which appears to be involved in interleukin 2 production and Ca2+ mobilization by Jurkat cells. The Tp45 molecule was identified by a monoclonal antibody, MX13, on the surface of either T3/TCR+ or T3/TCR− human T cell lines. Biochemical data showed that mAb MX13 precipitated a single polypeptide chain of 45 kDa both under reduced and nonreduced conditions from lysates of 125I‐surface‐labeled cells. Sequential immunodepletion experiments using lysates of 125I‐labeled T3/TCR+ cells showed that Tp45 was distinct from the α chain of the TCR complex. However, incubation of such cells with either anti‐T3 or anti‐TCR monoclonal antibody induced complete modulation of both the T3/TCR complex and Tp45. Conversely, complete modulation of both Tp45 and the T3/TCR complex was observed after incubation with anti‐Tp45 antibody. Functional studies showed that anti‐Tp45 antibody induced high levels of interleukin 2 production in Jurkat cells. In addition, incubation of these cells with the antibody resulted in Ca2+ mobilization from internal stores.Anti‐Tp45 antibody reacted with 3–19% peripheral blood (E‐rosette‐positive) T cells in individual donors. The magnitude of the proliferative response elicited by anti‐Tp45 antibody for peripheral blood T cells was lower than that induced by an anti‐T3 antibody. This observation is compatible with the idea that only a subpopulation of T cells is reactive with anti‐Tp45. Multicolor flow cytometry analysis showed that the Tp45+ cells belong preferentially to the T8 subset.
Production of hybridoma growth factor by human monocytes
Authors: Aarden Lucien A. , De Groot Els R. , Schaap Otto L. , Lansdorp Peter M. 
Published: March 2007

AbstractHuman mononuclear leukocytes produce a growth factor (HGF) for hybridoma and plasmacytoma cells. HGF has recently been proven to be identical to IFN‐β2, 26‐kDa protein and BSF‐2. HGF can be quantitated in a proliferation assay with the HGF‐dependent hybridoma cell line B13.29. By selection of an extremely sensitive variant of this cell line, we were able to measure HGF production of single cells. Limiting dilution analysis of the producing cells in combination with size, density and adherence characteristics showed that HGF is produced by monocytes and not by lymphocytes. There was no need for the monocytes to be stimulated but the cells did require the presence of serum. This serum requirement could be met by purified bovine serum albumin, but not by other proteins like ovalbumin or human γ‐globulin. HGF production in vitro by monocytes starts after 2 h of incubation and is completed within 24 h.
Experimental Trypanosoma brucei infections selectively suppress both interleukin 2 production and interleukin 2 receptor expression
Authors: Sileghem Maarten , Hamers Ramond , De Baetselier Patrick 
Published: March 2007

AbstractExperimental infections with Trypanosoma brucei AnTat 1.1. E not only account for a suppression of interleukin 2 (IL2) production, but also induce an impairment of IL2 receptor expression. Indeed, lymph node cells derived from infected mice failed to express IL2 receptors following mitogenic stimulation as compared to normal controls. This impairment was not attributed to a modulation of the number of T cells and was not caused by the presence of living parasites. Furthermore, the basal level of IL2 receptor expression could not be re‐established through the exogenous supply of recombinant IL2. This impairment of receptor expression was found to be mediated by suppressive cells that affect the relative number of receptor‐positive cells as well as the mean receptor density. On the other hand, the mitogen‐induced secretion of other T cell‐derived lymphokines was not inhibited during infection, indicating that the severe suppression of IL2 regulation was not attributed to a total paralysis of the T cell responsiveness.
Immuno‐electron microscopic characterization of large granular lymphocytes (natural killer cells) from rat liver
Authors: Bouwens Luc , Wisse Eddie 
Published: March 2007

AbstractThe immunocytochemical characteristics of large granular lymphocytes (LGL), isolated from the liver sinusoids of euthymic and athymic (nude) rats, were investigated in electron microscopy by the immunoperoxidase technique. The LGL were found positive for MRCOX‐8 (natural killer cells and cytotoxic/suppressor T cells) and negative for MRCOX‐19 (pan‐T marker) in both rat strains. The LGL were heterogeneous in the expression of the natural killer cell marker asialo‐GM1 which was found on 56% of the LGL from euthymic and on 71% of the LGL from athymic rats. LGL were easily distinguished from the other cells in the preparations, “conventional” lymphocytes and monocytes, thanks to their highly characteristic ultrastruc‐tural features, in particular by the presence of specific electron‐dense cytoplasmic granules and rod‐cored vesicles. These features have been described formerly for the so‐called “pit cells” and are more reliable than the classical LGL characteristics at the light microscopic level, i.e. the presence of azurophilic granules. Our results give further support for the existence of an important population of natural killer cells in the liver sinusoids.
Involvement of specific Lyt‐2+ T cells in the immunological control of experimentally induced murine cutaneous leishmaniasis
Authors: Titus Richard G. , Milon Geneviève , Marchal Gilles , Vassalli Pierre , Cerottini Jean‐Charles , Louis Jacques A. 
Published: March 2007

AbstractThe involvement of Lyt‐2+ T cells in the immunological control of cutaneous leishmaniasis was assessed by studying the course of the disease in mice in which the number of these cells was reduced by treatment with anti‐Lyt‐2 monoclonal antibody (mAb). Administration of anti‐Lyt‐2 mAb exacerbated Leishmania major‐induced cutaneous lesions in both genetically resistant and susceptible mice. This effect correlated with a drastic reduction in the number of specific Lyt‐2+ T cells generated during infection. These results, together with the observation that resistant mice possess higher numbers of specific Lyt‐2+ T cells in lymph nodes draining their lesions than susceptible mice, 3 weeks after infection, indicate that Lyt‐2+ T cells also play a role in the immunological control of Leishmania major‐induced lesions.
Interaction between the CD45 antigen and phytohemagglutinin. Inhibitory effect on the lectininduced T cell proliferation by anti‐CD45 monoclonal antibody
Authors: Bernabeu Carmelo , Carrera Ana C. , De Landázuri Manuel O. , Sánchez‐Madrid Francisco 
Published: March 2007

AbstractImmunoprecipitation studies from 125I‐labeled T cells, previously activated with the lectin phytohemagglutinin (PHA) from Phaseolus vulgaris, showed a preferential association between the CD45 glycoprotein family containing members of 220, 205, 190 and 180 kDa, and a protein of 33 kDa. This 33‐kDa protein, with an identical molecular mass as PHA, was not associated with other highly expressed molecules such as class I histocompatibility antigens (HLA‐A,B,C), transferrin receptor, CDw44 and CD11a. Further immunoprecipitation analysis from peripheral blood lymphocytes incubated with 125I‐labeled PHA confirmed the identification of the CD45‐associated 33‐kDa protein as the lectin PHA. These results prompted us to analyze the possible involvement of the CD45 molecules in the T cell activation process induced by PHA. Thus, two monoclonal antibodies specific for CD45 antigens were able to inhibit the T cell proliferation induced by the lectin. This inhibitory ability was exerted by affecting both the interleukin 2 production and the interleukin 2 receptor expression.
Human complement factor H: expression of an additional truncated gene product of 43 kDa in human liver
Authors: Schwaeble Wilhelm , Zwirner Jörg , Schulz Thomas F. , Linke Reinhold P. , Dierich Manfred P. , Weiss Elisabeth H. 
Published: March 2007

AbstractThe human complement factor H is an important factor in the control of the alternative pathway and also induces the stimulation of B cells and macrophages in vitro. Using a human factor H cDNA clone as probe, two factor H‐specific transcripts of 4.4 and 1.8 kb were detected in four human livers. Both mRNAs were found independently of the expression of an acute phase marker SAA, in these livers, indicating that their presence is not linked to an acute phase state. The shorter transcript was cloned in two cDNA plasmids H‐19 and H‐20, lacking only seven amino acids of the N‐terminus of the mature factor H protein. The deduced protein sequence showed that this protein is identical to the N‐terminal portion of the large classical factor H of 150 kDa mol. mass. Parallel to the finding that the N‐terminal sequence of factor H is expressed by two distinct mRNA species, evidence is presented that the C‐terminal sequence is also contained on two different transcripts, the common 4.4‐kb mRNA and an additional 1.0‐kb mRNA. A novel, short form of human complement factor H of 43 kDa was detected in human sera which represents the translation product of the 1.8‐kb factor H‐specific mRNA detected in human liver. Five distinct epitopes detected with 6 monoclonal antibodies are present on both the 150‐kDa factor H protein and the truncated 43‐kDa molecule. We conclude that additional H‐specific mRNAs are found in human liver and that at least one of them is translated yielding a truncated form of factor H.
A murine macrophage cell line, immortalized by v‐raf and v‐myc oncogenes, exhibits normal macrophage functions
Authors: Blasi Elisabetta , Radzioch Danuta , Durum Scott K. , Varesio Luigi 
Published: March 2007

AbstractIn vitro immortalized cell lines with the morphology and phenotype of mature macrophages (MΦ) have been generated by infecting freshly isolated bone marrow cells from C3H/HeJ mice with a recombinant retrovirus carrying v‐raf and v‐myc oncogenes. All of the clones obtained had MΦ‐like phenotypes, and one such clone, GG2EE, has been compared to normal MΦ to ascertain the effects of immortalization on the expression of the biological functions of the lines. GG2EE cells expressed cytotoxic activity against L5178Y, P815 or RL 1 target cells in response to stimulation with interferon‐γ (IFN‐γ) and heat‐killed Listeria monocytogenes; in contrast, they failed to kill YAC‐1 target cells. GG2EE cells did not constitutively express I‐A or I‐E antigens; nevertheless, I region‐coded antigens could be induced by IFN‐γ treatment. GG2EE cells produced interleukin 1 upon stimulation with a T cell‐derived lymphokine; they were weakly phagocytic, yet became highly phagocytic following IFN‐γ treatment. Since c‐fos mRNA is augmented in peritoneal exudate MΦ by protein kinase C activators but not by IFN‐γ, we evaluated the effects of calcium ionophore, phorbol myristate acetate, L‐α‐1‐oleoyl‐2‐acetoyl‐sn‐3 glycerol (OAG) and IFN‐γ on the levels of c‐fos mRNA in GG2EE cells. We found that calcium ionophore, PMA and OAG stimulation enhanced the expression of c‐fos mRNA, but IFN‐γ treatment did not. The kinetics of c‐fos induction in GG2EE cells were also comparable to those observed in peritoneal exudate MΦ. Overall, the GG2EE cell line has the same biological properties as normal tissue MΦ. Because it is capable of both constitutive and inducible MΦ‐like functions, this cell line provides a valuable tool for studying the molecular mechanisms controlling induction and/or expression of biological activities in MΦ. It is striking that a cell line immortalized in vitro by two oncogenes, v‐raf and v‐myc, behaves, according to the criteria mentioned above, like a normal MΦ population.
Phorbol diesters increase the phosphorylation of the leukocyte common antigen CD45 in human T cells
Authors: Autero Matti , Gahmberg Carl G. 
Published: March 2007

AbstractWe have studied the phosphorylation of the human leukocyte surface glycoprotein CD45, formerly known as leukocyte common antigen or T200, following activation of peripheral T cells with tumor‐promoting phorbol diesters. The cells were incubated with [32P]orthophosphate, treated with phorbol diesters, and the CD45 was immunoprecipitated using the monoclonal antibody T29/33. CD45 was weakly phosphorylated in nonactivated T cells, but a treatment of the cells with 10, 60 or 200 nM phorbol 12,13‐dibutyrate (PDBu) markedly increased the phosphorylation of the glycoprotein. This effect of PDBu was relatively selective for CD45 since the activation of the cells did not affect the phosphorylation of all membrane phosphoglycoproteins. The effect of another tumor promoter, phorbol 12‐myristate 13‐acetate (PMA), was comparable to that of PDBu, but a nontumor‐promoting phorbol derivative, 4α‐phorbol 12,13‐didecanoate, did not change the level of CD45 phosphorylation. The phosphorylation of CD45 was found to clearly increase after a treatment of T cells with 60 nM PDBu for only 30 s, and the phosphorylation reached its maximum in about 5 min.
In vivo effect of murine recombinant interleukin 3 on early hemopoietic progenitors
Authors: Kindler Vincent , Thorens Bernard , Vassalli Pierre 
Published: March 2007

AbstractNormal and irradiated mice were perfused with recombinant interleukin 3 (rIL 3) and the number of early hemopoietic progenitors (CFU‐S) was quantified in different organs. Normal mice perfused with rIL 3 for 3 or 7 days showed a dramatic increase in the number of CFU‐S in the spleen, liver and blood, while the bone marrow CFU‐S number was slightly decreased. The total number of CFU‐S per animal was only slightly increased; the major effect of rIL 3 perfusion was thus on the distribution of CFU‐S in the mice. Lethally irradiated mice injected with 5 × 104 syngeneic bone marrow cells and perfused with rIL 3 were killed after 10 days. A significant increase in both the number and size of the splenic colonies was observed. The CFU‐S content of these colonies, determined in a second set of irradiated mice, was increased by more than 25‐fold, indicating that in conditions of hemopoietic depletion, rIL 3 vastly increased the self‐renewal capacity of early progenitors.
Synergistic interaction between interleukin 4 and anti‐Bp50 (CDw40) revealed in a novel B cell restimulation assay
Authors: Gordon John , Millsum Michelle J. , Guy Graeme R. , Ledbetter Jeffrey A. 
Published: March 2007

AbstractHighly purified resting B lymphocytes stimulated for 3 days to high‐rate DNA synthesis by a synergistic combination of phorbol dibutyrate and ionomycin soon returned to quiescence once those signals had been removed. The maintenance of DNA synthesis in such cultures was found to provide a sensitive assay for revealing the factors that interact with cycling B cells. Whereas several activities ‐ namely, interleukin 4, anti‐Bp50 and a low molecular weight B cell growth factor ‐ were, by themselves, capable of prolonging DNA synthesis over a further day or so, no single factor was capable of sustaining the replication cycle out to day 6 of culture. By contrast, certain combinations of activities displayed significant synergy in the restimulation assay. The most striking observed was that between interleukin 4 and anti‐Bp50 where, by day 6, their combined effect on maintaining DNA synthesis in 3‐day stimulated cells was the same as having kept phorbol dibutyrate and ionomycin in the culture system. The implications of these findings are discussed.
Mott cells: a model to study immunoglobulin secretion
Authors: Alanen Anna , Pira Ulla , Colman Alan , Franklin Richard M. 
Published: March 2007

AbstractMott cells are plasma cells defective in immunoglobulin (Ig) secretion. They display this defect by accumulating Ig in the rough endoplasmic reticulum, detectable by Ig+ intracellular inclusion. We have previously produced hybridoma cell lines (Alanen, A. et al., Eur. J. Immunol. 1985. 15: 235) in which this phenotype is preserved, and shown the inability of these cells to secrete the Ig. In order to study this defect further, we fused these hybridoma cells with a x‐secreting hybridoma cell line, Sp1, and, using double selection with hypoxanthine, aminopterin, thymidine and ouabain, obtained hybrid cell lines expressing various combinations of the three Ig chains involved (Mott γ1, Mott χ and Sp1 χ chains). We studied the presence of Ig+ inclusions in these cells as well as Ig secretion by metabolic labeling and immunoprecipitation. All inclusion‐positive clones expressed both Mott heavy and Mott light chains with or without the Sp1 light chain, whereas none of the inclusion‐negative clones produced both Mott‐derived Ig chains. In all of the clones, even those with inclusions, the Ig secretion was at least partially rescued by the fusion. This occurred also in an inclusion‐positive clone which maintained the original Ig status of the Mott without Sp1 χ chain, indicating a complementation by the cell fusion of some cellular factor involved in Ig secretion. Furthermore, we injected Xenopus oocytes with mRNA isolated from three different original Mott cell hybridomas and could show secretion of the Ig, which is not secreted from the original Mott cells, from the oocytes.
T cell activation by cross‐linking anti‐CD3 antibodies with second anti‐T cell antibodies: dual antibody cross‐linking mimics physical monocyte interaction
Authors: Walker Christoph , Bettens Florence , Pichler Werner J. 
Published: March 2007

AbstractThe anti‐CD3 antibody BMA030 (IgG2a isotype) induces T cell activation and proliferation if an interaction with monocytes is provided. In contrast to other anti‐CD3 antibodies, it is unable to induce interleukin (IL)2 responsiveness through cross‐linking by plastic‐bound goat anti mouse Ig antibodies (panning). Cross‐linking BMA030 with a second anti‐T cell antibody is, however, able to induce IL 2 responsiveness in monocyte‐depleted T cell cultures. In this report we show that a large number of different antibodies are suitable for this dual antibody stimulation, and that the extent of proliferation corresponds to the percentage of T cells expressing the respective T cell antigen. Proliferation induced by low concentrations (0.1‐1 ng/ml) of other anti‐CD3 antibodies requires also cross‐linking with second anti‐T cell antibodies. The proliferative response of monocyte‐depleted T cells to two cross‐linked anti‐T cell antibodies plus added IL 2 is of the same magnitude as the one induced by anti‐CD3 antibodies plus monocytes. On the other hand, if monocytes are present, soluble anti‐CD2, ‐CD4, ‐CD8, ‐LFA‐1 antibodies (IgG1 or F(ab′)2 fragments) can inhibit OKT3 or BMA030‐induced T cell activation. Anti‐CD6 antibodies do not interfere with this monocyte‐dependent T cell stimulation. We conclude that dual antibody stimulation mimics the physical contact of T cells with monocyte membranes, where the T cell receptor CD3 complex is cross‐linked with neighboring structures (mainly so‐called adhesion molecules) through the interaction with respective counter‐structures on monocyte membranes. Dual antibody cross‐linking bypasses this interaction and can be used to stimulate IL2 responsiveness of antibodydefined T cells.