bluuebunny/crossref_metadata_2025 huggingface dataset:
Triggering of the phosphoinositide transduction pathway by a monoclonal antibody specific for the human γ/δ T cell receptor
Authors: Bismuth Georges , Faure Florence , Theodorou Ioannis , Debré Patrice , Hercend Thierry
Published: March 2007

We have developed a monoclonal antibody (mAb), termed anti‐TigammaA, which recognizes an antigenic determinant carried by a variable segment of the T cell receptor (TcR) γ chain. This determinant, encoded by the Vγ9 gene, is expressed on approximately 3% of peripheral blood lymphocytes. In the present study, we have found that binding of anti‐TigammaA mAb to its specific ligand results in the triggering of the phosphatidylinositol (PI) cycle‐related metabolic process. Indeed, an increased labeling of both phosphatidic acid and PI, related to an enhanced turnover of PI cycle‐dependent phospholipids, was observed following exposure of 32P orthophosphoric acid‐labeled cells to anti‐TigammaA mAb. In addition, there was a rapid rise in intracellular free calcium concentrations. Similar experiments have been performed previously on CD3+ TcRα/β−‐cells with an anti‐CD3 mAB. They predicted that signals produced by the interaction between the second TcR and its ligand(s) would be transmitted via the PI cycle‐linked intracellular second messengers. We confirm this hypothesis in an experimental system where stimulation occurs directly through the γ/δ receptor structure.
Protection of neutropenic mice from lethal Candida albicans infection by recombinant interleukin 1
Authors: Van Wout Jan W. 'T , Van Meer Jos W. M. Der , Barza Michael , Dinarello Charles A.
Published: March 2007

Natural and synthetic immunomodulators that increase nonspecific resistance to infection are also known to induce interleukin 1 (IL1) production. Previous studies have demonstrated a protective effect of recombinant human IL1β against death from infection caused by Pseudomonas aeruginosa. In the present study we investigated the effect of IL 1β or IL 1α on the survival of neutropenic mice with a lethal Candida albicans infection. Mice with cyclophosphamide‐induced neutropenia were injected with 3 × 105 C. albicans i.v. When 80 ng IL 1β was given as a single i.p. injection 24 h before the infection, survival compared to that in control animals was as follows: 100% vs. 97% at 24 h, 83% vs. 70% at 48 h and 70% vs. 23% at 72 h after the infection (p<0.01). The effect of IL1 was also apparent when it was given 1/2 h before or 6 h after the infection. The results obtained with 80 ng IL 1α given at 24 h before infection were similar to that obtained with IL 1β. The numbers of Candida cultured from the blood, liver, spleen, and kidney were not significantly different in IL 1β‐treated and control animals. Passive transfer of serum obtained from mice pretreated with IL 1 to recipient mice did not provide protection against a subsequent lethal candidal infection. In conclusion, the present study demonstrates that IL 1β and IL 1α prolong survival in neutropenic mice with a lethal C. albicans infection.
Modification of tumor cells by a low dose of Newcastle Disease Virus.
Authors: Hoegen Paul Von , Weber Ernst , Schirrmacher Volker
Published: March 2007

The present study elucidates the mechanism whereby viral xenogenization of highly metastatic ESb lymphoid tumor cells increases tumor immunogenicity and syngeneic tumor‐specific T cell responses in comparison to nonmodified tumor cells. It was found that the frequency of cytotoxic T lymphocytes specific for the ESb tumor‐associated transplantation antigen (TATA) and the cytotoxic anti‐tumor activity in bulk cultures of immune spleen cells were significantly increased (by factor 3 and 25, respectively) when using virus‐modified tumor cells. An amplified response was observed both in vivo and in vitro which might explain the demonstrated effectiveness of this approach for postoperative immunotherapy of ESb metastases.

For the stimulation of tumor‐specific cytolytic T lymphocytes (CTL) the ESb tumor cells which are highly metastatic were infected with an avirulent strain of the paramyxovirus Newcastle Disease Virus (NDV). Infection of ESb cells with low amounts of NDV was sufficient to lead to an increase in cytolytic activity of tumor‐specific CTL after sensitization in vivo and restimulation in vitro. In a sensitive limiting dilution mixed leukocyte‐tumor cell microculture system the direct effect of viral modification on the frequency and specificity of CTL was investigated. The number of ESb‐specific CTL per spleen could be raised from about 3300 (without modification) to 9100 by both in vivo and in vitro application of ESb‐NDV. One appliction of ESb‐NDV (in vivo or in vitro) increased the number of CTL to 4900 and 4600, respectively. In split‐type experiments it could be shown at the clonal level that viral modification did not alter the specificity of ESb‐specific CTL. No CTL clones directed against viral antigens or new antigenic determinants were detected. The results indicate that in this system the effect of viral xenogenization is not due to recognition of additional xenoor neoantigens. NDV modification instead led to a selective augmentation of the TATA‐specific CTL response. In this respect it is remarkable since other methods to increase ESb tumor immunogenicity such as mutagenization or co‐expression of minor H antigens were shown before to activate additional CTL clones without affecting the TATA‐specific CTL response.
The differentiation of O‐2A progenitor cells into oligodendrocytes is associated with a loss of inducibility of Ia antigens
Authors: Calder Virginia L. , Wolswijk Guus , Noble Mark
Published: March 2007

Current data suggest that some astrocytes, one of the 3 main types of macroglia in the central nervous system (CNS), can be induced by interferon‐y (IFN‐γ) to express major histocompatibility complex class I1 antigens (immune‐associated or Ia) and present antigen to T lymphocytes. In contrast, oligodendrocytes, another type of macroglia, cannot be induced to express Ia. The astrocytes which have been shown to express Ia are from a particular glial lineage and are called type‐1 astrocytes. The oligodendrocyte‐type‐2 astrocyte (0‐2A) lineage, which gives rise to oligodendrocytes, also gives rise to a second class of astrocytes called type‐2 astrocytes and the ability of type‐2 astrocytes or the common O‐2A progenitor cell to express Ia is not known. We have now found that both type‐2 astrocytes and O‐2A progenitor cells can be induced to express Ia by IFN‐Γ but Ia expression is not induced in oligodendrocytes in parallel cultures. Thus, it appears that differentiation of O‐2A progenitor cells into oligodendrocytes is specifically associated with a loss of inducibility of Ia. This apparent loss of the capacity for Ia expression, and presumably antigen presentation, in oligodendrocytes (the cells which produce myelin in the CNS) is of particular interest in view of the ability of immunization of myelin components to produce autoimmune‐mediated paralytic disease.
Rapid changes in target cell lysosomes induced by cytotoxic T cells: indication of target suicide ?
Authors: Pitsillides Andrew A. , Taylor Patricia M. , Bitensky Lucille , Chayen Joseph , Helen Muir I. , Askonas Brigitte A.
Published: March 2007

Although many studies have attempted to elucidate how cytotoxic T (Tc) lymphocytes cause the death of target cells, the mechanism is still controversial. In the present study the effect on the integrity of the lysosomes of the target cell has been investigated. We show here that the specific recognition and attachment of cloned type A influenza‐specific Tc cells to A/X31 influenza virus‐infected target cells caused rapid change in the amount of lysosomal naphthylamidase activity that was bound within the lysosomes, indicating that the lysosomal membianes in the target cells had been totally labilized. Target cells infected with type B influenza virus served as controls. We therefore suggest that the viral specificity of Tc, lymphocytes allows for recognition and intimate membrane contact with suitably infected targets. This intimate contact induces sufficient perturbation of the target cell plasma membrane so as to cause total labilization of the target cell lysosomes which could account for intracellular lysis.
The role of lymphocyte function‐associated antigen 1 (LFA‐1) in the adherence of T lymphocytes to B lymphocytes
Authors: Mazerolles Fabienne , Lumbroso Catherine , Lecomte Olivia , Le Deist Françoise , Fischer Alain
Published: March 2007

The functional role of the LFA‐1 molecule in the interaction between helper T lymphocytes and B lymphocytes was investigated using lymphocytes from patients with leukocyte adhesion deficiency, an inherited immunodeficiency characterized by a defective leukocyte expression of the LFA‐1, Mac‐1 (CR3) and p150,95 molecules. The ability of LFA‐1− T lymphocytes to provide antigen‐specific help for HLA−identical LFA‐1+ B lymphocytes was reduced while their antigen‐specific activation was normal. Antigen‐independent conjugate formation between resting, nonactivated LFA–1− T lymphocytes and LFA‐1+ B lymphocytes was impaired while LFA‐1−B lymphocytes bound LFA‐1+ T lymphocytes normally. Conjugate formation of activated LFA‐1− T lymphocytes was mostly mediated by the CD2‐LFA‐3 adhesion pathway while the ICAM‐1 molecule, a ligand of LFA‐1, had no function. These results demonstrate that LFA‐1 plays a major role in the cognate interaction between helper T lymphocytes and B lymphocytes that cannot be mediated instead by CD2 or other molecules on resting T lymphocytes.
Involvement in the initiation of T cell responses and structural features of an 85‐kDa membrane activation antigen
Authors: Schulz Thomas F. , Mitterer Manfred , Neumayer Heinz P. , Vogetseder Werner , Dierich Manfred P.
Published: March 2007

A monoclonal antibody, 7F7, directed at a recently described membrane activation antigen of 85 kDa was found to inhibit the T cell proliferation induced by an anti‐CD3 antibody, phytohemagglutinin A and concanavalin A. The T cell response to allogenic stimulator cells was also weakly inhibited. The inhibition of these T cell responses was only obtained if the antibody was added within the first 8 h (first 24 h in the case of the concanavalin A response) of culture. In addition the antibody inhibited the formation of cellular aggregates seen in stimulated cultures when added within the first 8 h. The membrane glycoprotein recognized by 7F7 is shown to have a slightly different molecular mass on cells of different lineage, a protein core of 55 kDa and to contain 30–50% of N‐linked as well as a small amount of 0‐linked carbohydrates and sialic acid residues. This study suggests that the highly glycosylated membrane activation antigen defined by antibody 7F7 could contribute to the contact between those cells which are involved in the initiation of T cell responses.
Interleukin 6, the third mediator of acute‐phase reaction, modulates hepatic protein synthesis in human and mouse. Comparison with interleukin 1 β and tumor necrosis factor‐α
Authors: Ramadori Giuliano , Van Damme Jo , Rieder Hartmut , Zum Büschenfelde Karl‐Hermann Meyer
Published: March 2007

Interleukin 6 ( IL6 ) is the new definition of a group of cytokines previously named according to their biological activity, e.g. B cell stimulatory factor 2 (BSF‐2), hybridoma plasmocytoma‐growth factor (HGF), interferon‐β2 (IFN‐β2), hepatocyte stimulating factor (HSF). It has recently been suggested that IL6 may represent the major mediator of actue‐phase protein response whereas IL 1β and TNF‐α could play a minor role. We compared the effect of the three cytokine on hepatic protein synthesis by performing in vitro as well as in vivo experiments. Human hepatoma cells (PLC/PRFS) were exposed to each cytokine separately for 20 h, and the effect was then studied at the protein and RNA level. All three cytokines reduced albumin and increased C3 and ceruloplasmin biosynthesis. The cytokines induced the same effect at the RNA level indicating that the modulation was pretranslational. The effect of the cytokines was specific since actin gene expression was not changed; furthermore the effect was blocked by specific antibodies against the cytokines. The effect of the single cytokines was dose and time dependent, and quantitatively comparable. None of the cytokines was able to alter αl‐anti‐trypsin synthesis. In vivo experiments with mice showed that IL 1β and TNF‐a both induce serum amyloid A (SAA) mRNA in the mouse liver and increase factor B (Bf) gene expression. Human recombinant IL6 induced SAA gene expression and it also had a weak positive effect on Bf gene expression after i.p. injection. These data demonstrate that the three cytokines studied are quantitatively and qualitatively comparable, and that all three are probably involved in acute‐phase protein response.
Interaction between lymphocytes and cultured high endothelial cells: an in vitro model of lymphocyte migration across high endothelial venule endothelium
Authors: Ager Ann , Mistry Shilaben
Published: March 2007

The interaction between lymphocytes and cultured high endothelial venule endothelium has been studied using light and electron microscopy. High endothelial cells (HEC) in monolayer culture bound lymphocytes 15‐200‐fold more efficiently than aortic endothelium, aortic fibroblasts or serum‐coated glass. Light microscopy of lymphocytes bound to HEC showed two populations. Type I lymphocytes were phase‐light, round and revealed no intracellular detail. Type II lymphocytes were phase‐dark and flattened. The nucleus and cytoplasm of type II cells were clearly visible under high power light microscopy. The relative positions of these two populations were determined by electron microscopy. Type I lymphocytes were attached to the surface of HEC and type I1 lymphocytes were flattened underneath. The transition from type I to type II was accompanied by a loss of surface microvilli and a redistribution of intracellular organelles. This suggested that lymphocytes actively migrated across the HEC layer in this assay.

The relationship between migrated lymphocytes and total adherent cells was determined by analysis of surface phenotype. Lymphocytes did not adhere randomly from the cell population plated. After 60 min there was an enrichment for B over T lymphocytes and the adherent T cell population was itself enriched for CD8′ cells over CD4′ cells. Migrated cells were, however, a random subpopulation of lymphocytes which adhered to HEC. This is clear evidence that migration was preceded by specific binding to HEC. Lymphocyte adhesion was independent of viable HEC showing that it was a passive event on the part of the endothelium. Lymphocyte migration was, however, completely dependent on viable high endothelium. We conclude that cultured HEC provide a biologically relevant, 3‐dimensional matrix which supports the specific adhesion of lymphocytes and actively promotes lymphocyte migration. These observations suggest to us that cultured high endothelium provides a novel in vitro model for the study of lymphocyte migration into lymph nodes from the blood.
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

Human 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

Membrane 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

One 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

Immunological 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

The 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

Negative 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

Murine 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

Tetanus 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

Steady‐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

Effects 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

CD4 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

The 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

Burkitt'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

A 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

Lysis 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.
Interleukin 4 and soluble CD23 as progression factors for human B lymphocytes: analysis of their interactions with agonists of the phosphoinositide “dual pathway” of signalling
Authors: Gordon John , Cairns Jennifer A. , Millsum Michelle J. , Gillis Steven , Guy Graeme R.
Published: March 2007

Human B lymphocytes pre‐activated for 24 h with a combination of phorbol dibutyrate [P(BU)2] and ionomycin were found to provide excellent targets for assessing the detailed action of B cell progression factors. Both recombinant interleukin 4 (IL4) and affinity‐purified 25‐kDa fragment of the CD23 molecule (sol‐CD23) were shown to be active in this assay. While the progression activity of IL4 was enhanced by continued co‐culture with P(Bu)2, that of sol‐CD23 was found to be more strictly dependent upon such a joint application with the phorbol ester. Similar requirements were observed for triggering cell‐cycle progression in the pre‐activated B cells when using a stimulating CD23 antibody. Ionomycin, in contrast to P(BU)2, did not augment either IL4 or sol‐CD23 in these assays but did enhance significantly the progression activity of an anti‐CDw40 antibody. When added to B cells concomitantly with, or prior to, a high dose of phorbol ester, IL 4 unexpectedly down‐regulated the subsequent mitogenic response to this agent whereas, when added 24 h later, IL4 up‐regulated such stimulations. The latter sequence of additions resulted in a particularly dramatic induction of CD23 at the B cell surface, much more so than seen when B cells were incubated with either IL4 alone or with IL 4 and P(Bu)2 together. This up‐regulation of surface CD23 was, in turn, mirrored by the appearance of large amounts of the soluble form of the molecule in such cultures. The findings are discussed with reference to possible mechanisms through which IL 4 and CD23 interact to exert their multiple actions on B cell regulatory pathways.
Physiology of murine B lymphocytes I. Life‐spans of anti‐m̀ and haptenated Ficoll (thymus‐independent antigen)‐reactive B cells
Authors: Udhayakumar Venkatachalam , Niranjan Gouda S. , Subbarao Bondada
Published: March 2007

We have evaluated the life‐span of B lymphocytes by measuring the functional reactivity of normal B cells upon transfer into xid mice, which do not respond to anti‐μ, fluoresceinated‐Ficoll (FL‐Ficoll) and 2,4,6‐trinitrophenyl aminoethylcarbamylmethyl Ficoll (TNP‐Ficoll). After 4 days of transfer only 30–40% of anti‐μ‐reactive cells decayed leaving behind 60–70% of B cells which appeared to decay slowly. Even 10 days after transfer ˜ 40% of anti‐γ‐reactive B cells can be recovered from the recipients. This result demonstrates the existence of heterogeneity in the life‐spans of anti‐μ‐reactive B lymphocytes and that a major population (60–70%) of B cells persists beyond 4 days. Interestingly, the short‐lived B cell subpopulation was not detected when the decay of the antigen‐specific B cells was studied. Thus, TNP‐Ficoll and FL‐Ficoll‐reactive B cells were found to be long lived and such B cells did not decline at all, even 5 months after transfer into xid mice.
A single cDNA encodes multiple Ly‐6 antigenic specificities
Authors: Korty Patricia E. , Cohen David I. , Shevach Ethan M.
Published: March 2007

To determine the relationship between the structure and function of proteins coded for by the Ly‐6 gene complex, we have transfected a cDNA for a Ly‐6.2 specificity into COS‐7 cells. A number of monoclonal antibodies which have been shown to be capable of inducing T cell activation and which have been previously considered to recognize distinct proteins all reacted with the same transfected gene product. The approach used in these studies should be useful to further elucidate the complexities of the Ly‐6 alloantigen system.
Interleukin 2 and low molecular weight B cell growth factor are T cell‐replacing factors for different subpopulations of human B cells*
Authors: Callard Robin E. , Smith Susan H.
Published: March 2007

Both recombinant human interleukin 2 (rhIL2) and low molecular weight B cell growth factor (BCGFlow) were shown to be T cell‐replacing factors (TRF) in specific antibody responses to influenza virus by human blood and tonsillar B cells. When B cells were separated into high and low‐density populations on Percoll gradients at 1.074 kg/l, IL2 was found to act as a TRF only on the low‐density B cells, whereas BCGFlow was a TRF for high‐density B cells with a lesser effect on low‐density B cells. Both populations of B cells responded well in the presence of T cells. The high‐density B cells could not be activated to respond to IL2 by either IL1, rhIL4 or by a CD22 monoclonal antibody known to enhance B cell activation. In contrast, a 24‐h preincubation with T cells and antigen appeared to prime high‐density B cells to respond to IL2. These results show that high‐density B cells can in fact respond to TRF, and that IL2 and BCGFlow, act on different populations of B cells which may be defined by prior exposure to T cells.
Cloned CD3+ TcRα/β− TiγA− peripheral blood lymphocytes compared to the Ti γA+ counterparts: structural differences of the γ/δ receptor and functional heterogeneity
Authors: Jitsukawa Setsuko , Triebel Frédéric , Faure Florence , And Christine Miossec , Hercend Thierry
Published: March 2007

We have assessed the organization of T cell γ rearranging genes (TRG) in circulating TcRγ/δ+ lymphocytes which do not express Vγ9‐encoded TiγA+ γ chain. Following purification of the minor TcRγ/δ+ TiγA− fraction, cloned cell lines were developed from peripheral blood of 5 individuals. Out of the 26 clones studied, only 3 TcRγ/δ+ TiγA‐ cells were found to express a disulfide‐linked C1‐encoded γ chain. The remaining 23 TiγA− clones with a C2‐encoded nondisulfide‐linked receptor were found to display rearrangements of various V genes to 52 segments on both chromosomes; there was no predominance of a unique rearrangement even though the TRG‐V3 and ‐V4 genes belonging to subgroup I were frequently employed. Together, these findings further strengthen the hypothesis that lymphocytes with a Cγ1 encoded chain are produced earlier in T cell ontogeny than the Cγ2 counterparts. The “non‐major histocompatibility complex (MHC) requiring” (i.e., “natural killer‐like”) cytotoxicity mediated by many TcRγ/δ+ TiγA− cells appeared to be very low as compared to that of Ti γA+ clones. Yet, treatment by the OKT3 monoclonal antibody revealed a strong lytic potential in the TiγA− lymphocytes with little, if any, natural killer‐like activity. Thus, with respect to the latter function, a substantial heterogeneity is found in cells expressing distinct γ chains. In an attempt to characterize undefined specificities of TiγA− lymphocytes, they were screened against a panel of Epstein‐Barr virus‐transformed B cell lines homozygous for HLA‐DR1 to DR10 determinants; one of the clones was found to recognize DR7. In light of reports from other groups describing class I‐related specificities, it is apparent that TcRγ/δ+ lymphocytes are able, like the TcRα/β+, to recognize and kill target cells through either an MHC‐dependent (with involvement of either class I or class II gene products) or a non‐MHC‐requiring pathway.
Towards an idiotype vaccine against mammary tumors. Induction of an immune response to breast cancer‐associated antigens by anti‐idiotypic antibodies
Authors: Smorodinsky Nechama Ina , Ghendler Yoseph , Bakimer Ronit , Chaitchuk Samario , Keydar Iafa , Shoenfeld Yehuda
Published: March 2007

Previously we have reported on the production of two sets of human monoclonal antibodies reacting with mouse mammary tumor virus (MMTV) and human mammary tumor virus (HuMTV) cross‐reacting antigens. B11 is a monoclonal IgG generated by the human‐human hybridoma technique using axillary lymph node of breast cancer patients. 4.616 is a monoclonal IgG established by the mouse‐human hybridoma procedure using peripheral blood lymphocytes of a healthy investigator working with the breast cancer cell line T47D which secretes HuMTV antigens. Two anti‐idiotypic (Id) antibodies were produced by immunizing rabbits with B11 or 4.616. Following exhaustive adsorption on unrelated human‐Ig, fetal calf serum and purification on B11 or 4.616 affinity columns, the anti‐Id antibodies were shown to react specifically with their respective Id. The binding of these anti‐Id antibodies to the respective Id was specifically inhibited by prior incubation of the Id with MMTV and/ or HuMTV antigens

Rabbit anti‐B11 and rabbit anti‐4.6/6 anti‐Id antibodies were employed to immunize female C3Heb mice. Following immunizations, humoral and cellular immune responses to MMTV‐related antigens could be demonstrated. The sera of the mice contained anti‐MMTV antibodies and delayed‐type hypersensitivity was specifically expressed when irradiated cells of the Mm5MT line (which carry surface MMTV antigens) were injected

Our results support the notion that anti‐Id antibodies harboring the internal image can immunize animals against tumor cells bearing on their surface viral‐associated antigens.