bluuebunny/crossref_metadata_2025_split huggingface dataset:
Proteins in normal and malignant cells, cross‐reacting with the latent membrane protein encoded by Epstein‐Barr virus
Authors: Hatzubai Ada , Lerner Richard A. , Klein George , Sulitzeanu Dov 
Published: March 2007

AbstractHuman B lymphocytes transformed by infection with the Epstein‐Barr virus (EBV) express a new membrane protein of 63 kDa (latent membrane protein, LMP) encoded by the virus. The function of this protein in the virus‐cell interaction is not known. In this work we have identified in EBV− human and mouse cell molecules which cross‐react with LMP. Two types of reagents were employed: (a) antibodies against LMP‐derived synthetic peptides, affinity purified from antisera against a fusion protein containing the carboxy half of the LMP molecule and (b) antisera prepared by immunizing rabbits directly with the peptide conjugates. Cross‐reactions were determined by radioimmunoblotting experiments. At least six molecules (M, = 110, 85, 63, 53, 45 and 23 kDa), present in a variety of human cells (peripheral blood lymphocytes, B cell lines and epithelial cell lines) were found to cross‐react with the LMP‐derived peptides. Cross‐reacting proteins were also identified in normal mouse tissues. The specificity of the cross‐reacting antibodies was confirmed by inhibition experiments with the corresponding peptide. Furthermore, antibodies eluted from individual bands were shown to bind to the same band when reacted with new blots of the same extracts. Our data suggest that normal cells contain a family of highly conserved proteins cross‐reacting with the LMP molecule. If, indeed, these proteins share common functions, their study may lead the way to unraveling the function of LMP.
Distribution of membrane cofactor protein of complement on human peripheral blood cells. An altered form is found on granulocytes
Authors: Seya Tsukasa , Ballard Laura L. , Bora Nalini S. , Kumar Vijaya , Cui Wenying , Atkinson John P. 
Published: March 2007

AbstractMembrane cofactor protein (MCP) of human complement is an iC3/C3b‐binding glycoprotein with a characteristic two‐band (63 kDa and 55 kDa) pattern on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). Using affinity chromatography, it has been found on human mononuclear cells and platelets. MCP has been purified and shown to be a cofactor for the I‐mediated cleavage of C3b. A rabbit polyclonal antibody was produced to the purified protein and this reagent employed to analyze the distribution of MCP on human peripheral blood cells. Flow cytometric analysis indicated that MCP is unimodally present on all platelets, granulocytes, T helper lymphocytes, T suppressor/cytotoxic lymphocytes, B lymphocytes, natural killer cells and monocytes but not erythrocytes. The presence of MCP on granulocytes was unexpected. To evaluate this, MCP was isolated by immunoprecipitation and analyzed by SDS‐PAGE followed by autoradiography. The M1 of granulocyte MCP was that of a single broad band in which the typical two‐band pattern could not be distinguished. Alterations in the conditions of the affinity column procedure increased the efficiency of the isolation of monocyte MCP and led to the reproducible isolation of granulocyte MCP. These results indicate that MCP of granulocytes has both structural and functional differences compared to MCP of plateletes and mono‐nuclear cells. The wide distribution of MCP among peripheral blood cells supports the concept that MCP is important in the protection of host cells from complement‐mediated damage.
Both interleukin 1 and tumor necrosis factor enhance thymocyte proliferation
Authors: Hurme Mikko 
Published: March 2007

AbstractOne of the biological activities of interleukin 1 (IL1), the lymphocyte‐activating function, is usually quantitated by measuring the effect on thymocyte proliferation in the presence of a T cell mitogen. Tumor necrosis factor (TNF) is also produced by activated macrophages, and it has recently been shown that it can enhance the proliferation of mature, human T cells. To analyze the role of these macrophage products in the proliferative response of murine thymocytes, we have tested the effects of purified (produced by the recombinant DNA techniques) IL 1 and TNF in thymocyte cultures, where the cell concentration, mitogen as well as the accessory cell amount was varied. The data obtained show that both IL 1 and TNF can facilitate the thymocyte proliferation, but the effect of TNF required a stronger T cell activation signal (a higher phytohemagglutinin, PHA, dose or concanavalin A instead of PHA) to become optimal. Moreover, the effect of IL1 was totally abolished by depleting the la+ accessory cells from the thymocytes, while that of TNF remained intact. IL 1 and TNF acted synergistically in this activation and this effect was so strong that thymocyte proliferation started even in the absence of the mitogen. Thus, the data suggest that these cytokines act on different steps of the T cell activation process.
Secondary antibody responses to thymus‐independent antigens. Decline and life‐span of memory
Authors: Colle Jean‐Hervé , Truffa‐Bachi Paolo , Freitas Antonio A. 
Published: March 2007

AbstractImmunological memory has been defined by the finding that upon a secondary injection of an antigen into an animal the immune response obtained differs from the response produced after the first inoculation of the antigen, independent of the length of time that can elapse between the first and second contact with antigen. In this report we have investigated the life‐span of memory to a thymus‐independent antigen, trinitrophenylated lipopolysaccharide (TNP‐LPS), using a cell transfer system that allows the study of the function of isolated LPS‐reactive “memory” B cells from C57BL/6 mice in histocompatible LPS‐nonresponder C57BLAOScCr hosts. We found that the longer the elapse of time between the transfer of TNP‐LPS‐primed C57BL/6 cells and the challenge of hosts with TNP‐LPS, the lower the anti‐TNP serum antibody level of the secondary response, i.e. in the absence of antigen, TNP‐LPS memory cells have a short life‐expectancy in the adoptive hosts as they do not persist for more than one or two weeks after transfer. Our present results suggest that induction and long‐term persistence of memory to TNP‐LPS in adoptive hosts cannot be solely explained by the long life‐span of a subpopulation of antigen‐specific memory B cells, but rather through the continuous recruitment of newly formed cells and probably antigen persistence.
In vivo dynamics of CD4–8– thymocytes. Proliferation, renewal and differentiation of different cell subsets studied by DNA biosynthetic labeling and surface antigen detection
Authors: Penit Claude , Vasseur Florence , Papiernik Martne 
Published: March 2007

AbstractThe proliferative status of CD4 −8− thymocyte subsets was determined by in vivo or in vitro labeling with bromodeoxyuridine (BrdUrd), a nonreutilized thymidine analogue detectable with a monoclonal antibody, simultaneously with relevant surface proteins. An actively cycling subset [J11d, interleukin 2 receptor‐positive (IL2R)] was defined, besides a relatively resting one (J11d‐, Pgpl, T cell receptor‐positive). Continuous per os administration of BrdUrd showed that 85% only of CD4−8− thymocytes were labeled in 6 days confirming the existence of a relatively long‐term resting subset. By contrast, CD48 thymocytes were all labeled in 3–4 days. Observation of labeled CD4−8− cells after pulse labeling showed an immediate decrease of their absolute number per thymus, confirming their low autorenewal capacity. However, a small number of labeled cells which were hydroxyurea or colchicine resistant remained CD4−8− for several days and progressively acquired surface expression of IL2R. IL2R expression by cycling CD4−8− cells during thymus regeneration after antimitogenic drug treatment was rapid, but very transient.According to these results most CD4−8− thymocytes appear as largely engaged in a proliferation‐dependent differentiative process, and do not behave as true stem cells. Consequently, this subset is principally renewed by thymic immigration of exogenously produced resting cells. However, a tenfold expansion of CD4−8− cells was found in the fetal and regenerating thymus, suggesting two proliferative phases during intrathymic CD4−8− cell maturation, the first one yielding to cell expansion and the second to cell differentiation. A tentative evaluation of daily cell immigration is proposed starting with the determination of the number of cells beginning DNA synthesis each day. A global model is finally discussed by confronting our kinetic results with the known reconstitution capacities of CD4−8− thymocyte subsets.
Cyclic AMP has the ability to influence multiple events during B cell stimulation
Authors: Holteδ Harald , Torjesen Peter , Blomhoff Heidi Kiil , Ruud Erik , Funderud Steinar , Smeland Erlend B. 
Published: March 2007

AbstractNegative regulators of cellular proliferation are important in maintaining a balanced growth control. In this study we have examined the effects of the diterpene forskolin on various parameters of B cell activation. Forskolin is known to elevate intracellular adenosine 3′,5′‐cyclic monophosphate (cAMP) levels and thereby to influence B cell stimulation. We found that forskolin exerted an inhibitory effect on early as well as late events during stimulation of resting normal human B cells. Cells were activated either by antibodies to surface immunoglobulins (anti‐μ), by the monoclonal antibody 1F5 reactive with the CD20 antigen or by 12‐O‐tetradecanoylphorbol 13‐acetate. While anti‐μ stimulation induces increased phosphatidylinositol (PI) turnover and [Ca2+Ii fluxes, the latter two reagents confer an activation of B cells independent of the PI/Ca2+ pathway. We found a clear inhibitory effect of forskolin on the anti‐p‐induced PI turnover and [Ca2+Ii fluxes as well as on later parameters of cell activation. There was also a clear inhibition of G1 entry and DNA synthesis when PI/Ca2+‐independent activation was employed, indicating that cAMP interferes with B lymphocyte stimulation in several ways. Importantly, forskolin maintained its inhibitory effect when added late after anti‐μ stimulation, implying an effect also at multiple stages of activation. When examining the inhibitory effect of forskolin on neoplastic B cells, we found essentially no differences from the responses in normal cells.
Selective production of interleukin 3 (IL 3) and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) in vitro by murine L3T4 T cells: lack of spontaneous IL 3 and GM‐CSF production by Ly‐2−/ L3T4− lpr subset
Authors: Davignon Jean‐Luc , Kimoto Makoto , Kindler Vincent , Kossodo Sylvie De , And Pierre Vassalli , Izui Shozo 
Published: March 2007

AbstractMurine spleen and lymph node L3T4 T cells were found to spontaneously produce high levels of interleukin 3 (IL3) and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) in cultures containing 10% fetal calf serum (FCS) in the absence of other stimulation. The IL3 and GM‐CSF activities in culture supernatants peaked between the fifth and seventh day of culture. The specificity of the bioassays was attested by the use of rabbit anti‐IL3 and anti‐GM‐CSF antibodies, as well as by the detection of a maximal accumulation of IL3 and GM‐CSF mRNA on the fourth day. In contrast, no significant activities of IL 2, IL 4 or interferon‐γ were detected in these culture supernatants. The markedly limited production of IL3 and GM‐CSF in cultures performed in l% autologous normal mouse serum and the inhibitory effect of anti‐Ia or anti‐L3T4 monoclonal antibody strongly suggest that the selective production of most, if not all IL3 and GM‐CSF by L3T4′ T cells is a result of activation of L3T4+ T cells by fetal calf serum. All the strains of mice tested except athymic nude mice produced substantial amounts of IL3 and GM‐CSF during the culture. This is in contrast to a previous report (Palacios, Eur. J. Immunol. 1984. 14: 599), indicating that only spleen cells of the MRL strain homozygous for the lpr gene spontaneously release IL3 in cultures. We found that spleen and lymph node cells from MRL/MpJ‐lpr/lpr or C57BL/6J‐lpr/lpr mice released, in fact, much less IL3 and GM‐CSF in cultures. This was, however, due to the high proportion of the peculiar lpr Ly‐2–1 L3T4− T cells in spleen and lymph nodes, since after depletion of this lpr T cell subset, lymph node cells from C57BL/6J‐lpr/lpr mice produced IL 3 and GM‐CSF at levels comparable to those in C57BL/6J‐+/+ mice. These results further support the notion that the lpr Ly‐2−/L3T4− T cell subset is immunologically nonfunctional and its accumulation dilutes functional L3T4+ T cells in mice bearing the lpr mutation.
The Fc valency of an immune complex is the decisive factor for binding to low‐affinity Feγ receptors
Authors: Klaassen Robert J.L. , Goldschmeding Roel , Tetteroo Pedro A.T. , Kr Von Dem Borne Albert E.G. 
Published: March 2007

AbstractTetanus toxoid (TT) was complexed with two human monoclonal antibodies. The antibodies recognized different, nonrepeating epitopes. The complexes formed were characterized by gel filtration and isokinetic sucrose density gradient centrifugation. It was found that in antigenic excess the separate antibodies formed a complex of one antibody molecule and two TT molecules [IgG1(TT)2 and IgG3‐(TT)2]. In cases where equal amounts of TT and both antibodies were mixed, a dimeric complex [IgG1(TT)2‐IgG3] was formed. The binding of these immune complexes to human neutrophils and eosinophils was studied. Whereas the immune complexes containing one antibody did not bind to either cell type, the two‐antibody complex bound to both. This indicates that not the sterical change in the Fc part of an antibody molecule after binding an antigen, but the Fc valency of an immune complex is the decisive factor in Fc receptor interaction with neutrophilic and eosinophilic granulocytes.
Stimulation‐dependent lymphokine mRNA levels in human mononuclear cells
Authors: Gauchat Jean‐François , Walker Christoph , De Weck Alain L. , Stadler Beda M. 
Published: March 2007

AbstractSteady‐state mRNA levels for lymphokines were studied in human peripheral blood mononuclear cells stimulated by various agents. The pattern of mRNA levels differed according to the way in which cells were stimulated or activated. Stimulation by anti‐CD3 antibodies led to increased mRNA levels for interferon‐γ but only extremely low levels of interleukin 2 mRNA were detected. In order to observe levels of inter‐leukin 2 mRNA, it was necessary to use phorbol myristate acetate (PMA) in addition to either lectins or anti‐CD3 antibodies. PMA by itself was already able to induce high levels of mRNA for granulocyte macrophage colony‐stimulating factor. Most interestingly, different patterns of lymphokine production were obtained with stimuli yielding the same number of activated cells and the same ratio of activated CD4 and CD8 cells. Thus, different T cell stimuli induced distinct patterns of lymphokine mRNA levels.
Effects of tumor necrosis factor on the interferon‐γ‐induced major histocompatibility complex class II antigen expression by human endothelial cells
Authors: Leeuwenberg Jet F. M. , Damme Jo Van , Meager Tony , Jeunhomme Trudy M. A. A. , Buurman Wim A. 
Published: March 2007

AbstractEffects of tumor necrosis factor‐a (TNF) and interferon‐β (IFN‐β) on the IFN‐γ‐induced major histocompatibility complex (MHC) class II expression on human umbilical vein endothelial (HUVE) cells are reported. TNF inhibited the induction of MHC class XI expression by IFN‐γ markedly, when added before or simultaneously with IFN‐γ. However, TNF added to the cells 24 h after IFN‐γ enhanced the expression of MHC class II antigens. IFN‐β inhibited the MHC class II expression irrespective of the time at which it was added to the cells. Addition of IFN‐β, TNF, IFN‐γ, and the combination of IFN‐β and IFN‐γ or TNF and IFN‐γ, resulted in all cases in an enhanced MHC class I antigen expression. Antibodies directed against IFN‐β reversed the inhibition of MHC class II expression by both TNF and IFN‐β. The enhancing effect of TNF could not be inhibited by anti‐IFN‐β indicating that TNF mediates enhancement of IFN‐γ‐induced MHC class II expression via a pathway other than IFN‐β. The role of TNF in the up‐regulation as well as in the down‐regulation of MHC class II expression in inflammatory processes is discussed.
CD4CD45R cells are preferentially activated through the CD2 pathway
Authors: Matsuyama Takami , Anderson Paul , Daley John F. , Schlossman Stuart , Morimoto Chikao 
Published: March 2007

AbstractCD4 cell subsets, CD4CD45R(CDw29−) cells and CD4CD45R−(CDw29) cells, can be differently triggered by various stimuli and possess distinct functions. In the present study, cell activation in CD4CD45R and CD4CD45R− subsets mediated by CD3‐Ti antigen‐receptor complex or CD2 molecule were examined by using anti‐CD3 antibody or pairs of anti‐CD2 antibodies (anti‐T112, and anti‐T113 antibodies). The results showed that CD4CD45R cells were preferentially activated through the CD2 pathway, whereas both subsets were equally activated through the CD3‐Ti antigen‐receptor pathway when a second signal such as monocytes or interleukin 2 was present. The different responsiveness of CD4CD45R and CD4CD45R‐ subsets through the CD2 molecule did not appear to be due to differences in the distribution or number of T112 and T113 determinants. These data suggest that some part of the functional diversity of CD4 cell subsets might be explained by the difference in cell activation through the CD2 molecule.
Induction of differentiation in human leukemic b cells by interleukin 2 alone: differential effect on the expression of μ and j chain genes
Authors: Emilie Dominique , Karray Saoussen , Merle‐Béral Hélène , Debré Patrice , Galanaud Pierre 
Published: March 2007

AbstractThe effects of interleukin 2 (IL2) on the proliferation and differentiation of B cells were analyzed separately using cells from two patients suffering from B‐type chronic lymphocytic leukemia. The monoclonal B cells from these patients exhibited an opposite pattern of responsiveness upon in vitro culture with IL2 in the absence of other stimuli. In the first patient, IL2 alone was able to induce DNA synthesis and no Ig production. In the second patient, although no DNA synthesis was detected, B lymphocytes synthesized IgM upon stimulation with IL 2 alone. Analysis of mRNA levels was performed on the cells of this latter patient after culture without or with IL2. In the presence of IL 2 we observed a strong enhancement of Cμ gene expression associated with an increase of the ratio between the secreted form and the membrane‐bound form of μ mRNA. In contrast IL2 induced only a marginal enhancement of J chain mRNA. Thus, terminal B cell differentiation of selected monoclonal B cells can be obtained in the absence of DNA synthesis and IL2 alone can mediate this process. Moreover, IL2 can act at selective steps of the molecular events associated with IgM production. These results document the multiple effects of a given IL on the events leading to antibody production and strongly suggest that they can be conditioned by the maturation stage of a given responding cell.
BURKITT'S LYMPHOMA CELL LINES PRODUCING TRUNCATED P IMMUNOGLOBULIN HEAVY CHAINS LACKING PART OF THE VARIABLE REGION
Authors: Cogné Michel , Mounir Samir , Preuďhomme Jean‐Louis , Nau Francois , Guglielmi Paul 
Published: March 2007

AbstractBurkitt's lymphoma cell lines Ly91, Ly47 and JBL2 contained intracytoplasmic μ chains without light chains and variably expressed membrane μ chains. All three cell lines produced similarly truncated heavy chains with an apparent molecular mass of 64 kDa instead of the normal 74 kDa. Both the intracellular and secreted forms of the μ chains were similarly truncated. The membrane and the secreted forms of μ mRNAs were shorter than normal. The cDNAs contained a leader sequence, followed by about one third of a variable region (VH), then by the constant region (Cμ). Interruption of the variable region took place near the end of the framework region 1 (FR1) in Ly47 and JBL2, and within the complementarity determining region 1 (CDR1) in Ly 91. In the three lines, the joining between VH and Cμ maintained the normal open reading frame throughout the variable and constant regions.
ANTIGEN‐INDEPENDENT ACTIVATION OF T CELLS MEDIATED BY A NOVEL CELL SURFACE HETERODIMER (TPL35‐145)
Authors: Isler Patrick , Salvi Suzanne , Rapin Christophe , Giuffrè Laura , And Jean‐Charles Cerottini , Carrel Stefan 
Published: March 2007

AbstractA new heterodimeric structure, Tp135‐145, which can mediate interleukin 2 (IL2) production and Ca2+ mobilization by Jurkat cells is described. This structure was identified by a monoclonal antibody, MX24, on the surface of either T3/TcR+ or T3/TcR− human T cell lines as well as on B cell lines.Biochemical studies showed that antibody MX24 precipitated two polypeptide chains of 135 and 145 kDa, respectively, in lysates from 125I‐labeled T cells. After reduction the 135‐kDa polypeptide chain shifted to 140 kDa, whereas the molecular mass of the other polypeptide remained unchanged. The apparent molecular masses of the desialylated polypeptides differed by 5 kDa. No common peptide fragments between the two polypeptide chains were found after limited proteolysis by Staphylococcus aureus V8 protease.The expression of Tp135‐145 was independent of the expression of the T3/TcR molecular complex. Incubation of Jurkat cells with anti‐TcR or anti‐T3 monoclonal antibody induced complete modulation only of the T3/TcR complex but not of Tp135‐145. Conversely complete modulation of Tp135‐145 was observed after incubation of these cells with MX24 antibody. Functional studies showed that anti‐Tp135‐145 antibody MX24 induced high levels of IL2 production in Jurkat cells. In addition, incubation of these cells with MX24 resulted in Ca2+ mobilization from internal stores. In peripheral blood, Tp135‐145 was found to be expressed by 39%‐76% of resting T cells in individual donors. Two‐color flow microfluorimetry showed that the Tp135‐145′ cells were equally distributed on the CD4+ and CD8+ subsets.Incubation of peripheral blood T cells with antibody MX24 resulted in IL 2 production and cell proliferation. Taken together these results suggest that Tp135‐145 is a novel surface molecule involved in antigen‐independent pathway of T cell activation.
IMPORTANCE OF ANTIGEN SPECIFICITY FOR COMPLEMENT‐MEDIATED LYSIS BY MONOCLONAL ANTIBODIES
Authors: Bindon Carol I. , And Geoffrey Hale , Waldmann Herman 
Published: March 2007

AbstractLysis of human lymphocytes by autologous complement had been studied using a range of monoclonal antibodies against different antigens. Antigen specificity (and not antibody isotype) was the most important factor which influenced cell lysis and this could not be accounted for merely by differences in surface density between antigens. Three antigens with comparable surface density were studied in detail: CAMPATH‐1 (lytic), major histocompatibility complex class I (lytic) and leukocyte common antigen (poorly lytic). Clq binding was roughly proportional to antibody binding and dependent on antibody isotype. However, the lytic antibodies were much better able to bind and activate whole C1 than the poorly lytic ones. This result would not have been predicted from traditional concepts of complement activation but can be interpreted in the light of models for C1 activation which involve Fc‐Fc interactions, Fc‐Clr2s2 interactions and a critical Clq stein‐arm angle for C1 binding and activation.