bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phorbol 12,13‐dibutyrate enhances lateral redistribution of membrane glycoproteins in human blood lymphocytes
Authors: Patarroyo Manuel , Gahmberg Carl G. 
Published: February 2007

AbstractNanomolar concentrations of 4β‐phorbol 12,13‐dibutyrate markedly enhanced the redistribution of concanavalin A receptors, the common leukocyte antigen and the Lyt‐3 antigen in human blood lymphocytes, as measured by cap formation. The effect on the lateral mobility of these cell surface molecules was dose dependent and occurred within a few minutes of treatment. 12‐O‐Tetradecanoyl phorbol 13‐acetate, another tumor promoter, was similarly active. 4α‐Phorbol 12,13‐didecanoate, which does not have tumor‐promoting activity, did not enhance cap formation. The effect of various drugs and treatments indicated that the phorbol ester‐enhanced cap formation was energy and temperature dependent and required functional microfilaments. Retinoic acid, an antitumor‐promoting agent, was inhibitory and trifluoperazine, an inhibitor of calmodulin‐dependent processes, had a minor inhibitory effect. Protein secretion and synthesis, extracellular Ca2+/Mg2+ and functional microtubules did not seem to be involved. The enhanced capping was inhibited by the alkylating agents tosyl phenylalanyl chloromethyl ketone and tosyl lysyl chloromethyl ketone but not by other protease inhibitors. The effect of various amino acid derivatives suggested the participation of an esterase. A comparative study of dose response, kinetics and sensitivity to drugs indicated a direct correlation between the phorbol 12,13‐dibutyrate‐enhanced redistribution of membrane glycoconjugates and the phorbol ester‐induced binding (adhesion) between human blood lymphocytes, a phenomenon previously described.
Sequential development of helper and suppressor functions, antibody titers and functional avidities to a streptococcal antigen in rhesus monkeys
Authors: Lehner Thomas , Caldwell Jill , Avery Janet 
Published: February 2007

AbstractSequential development of antibody titer, functional avidity, helper and suppressor activities were investigated in rhesus monkeys. These were immunized with a single dose of 0.1 μg to 10 mg of a streptococcal protein antigen (SA) in aluminium hydroxide. The IgG antibody titers followed the classical pattern first established in mice, of high‐dose and low‐dose tolerance with intermediate doses of immunity. This was correlated with a similar pattern of functional avidity of IgG antibodies, as measured by a dissociation assay. Helper and suppressor functions were assayed in parallel by inducing the corresponding factors from monkey lymphocytes in Marbrook flasks and testing the factors which cross the species barrier in cooperative cultures with CBA mouse spleen B cells. A progressive modulation of helper and suppressor activities was elicited by the increasing doses of SA, during the initial 28 days after immunization. Thus, dominant suppressor with minimal helper activity, IgG antibody titer and functional avidity were elicited by 0.1 μg SA. However, 1 or 10 μg SA induced dominant helper with minimal or transient suppressor activity and high IgG antibody titers and functional avidity. Somewhat intermediate responses were elicited by 100 μg SA, but 1 mg and especially 10 mg SA induced dominant suppressor and minimal helper activity, with low IgG antibody titers and functional avidities. When the immune response was established, about 28 days after immunization, the intermediate dose of SA elicited IgG antibodies with high titer and functional avidity, high T cell helper but low suppressor activities. In contrast, both high‐ and low‐dose SA induced partial tolerance, with low IgG antibody titer, functional avidity and T cell helper activity. These studies suggest cyclical development of helper and suppressor functions during the 4 weeks after immunization. The emergence of a dominant helper or suppressor function is antigen dose dependent.
Immunoregulation of lysozyme‐specific suppression. I. Induction and suppression of delayed‐type hypersensitivity to hen egg‐white lysozyme
Authors: Colizzi Vittorio , Doria Gino , Adorini Luciano 
Published: February 2007

AbstractSubcutaneous immunization with hen egg‐white lysozyme (HEL) in complete Freund's adjuvant induces, both in antibody responder and nonresponder mice, a classical delayed‐type hypersensitivity (DTH) reaction evaluated as footpad swelling. This response can be specifically transferred to naive recipients by Lyt‐1+2− T cells and passive transfer is restricted by genes mapping in or to the left of the I‐A region of the H‐2 complex.Fine antigenic specificity analysis shows that HEL‐primed T cells mediating DTH recognize ring‐necked pheasant egg‐white lysozyme, a lysozyme closely related to HEL, but fail to respond to human lysozyme, differing from HEL at 40% amino acid residues. Complete cross‐reactivity between native and denaturated (reduced and carboxymethylated) HEL is exhibited by T cells involved in the DTH response. Subcutaneous injection of HEL coupled to spleen cells is also able to induce antigen‐specific and genetically restricted DTH responses whereas the same cells administered by i.v. or i.p. route induce predominantly suppressor T cell activation. These suppressor T cells specifically inhibit the induction phase of DTH reactivity to HEL.
Frequencies of phosphorylcholine‐specific and T15‐associated 10/13 idiotope‐positive B cells within lipopolysaccharide‐reactive B cells of adult BALB/c mice
Authors: Lévy Martine 
Published: February 2007

AbstractThe frequencies of lipopolysaccharide‐reactive B lymphocytes in adult BALB/c spleen cells were determined by limiting dilution experiments to be between 1 in 50 and 1 in 100. Within this reactive population, the frequencies of B lymphocytes specific for phosphorylcholine (PC) and/or binding a TEPC 15‐associated idiotope‐specific monoclonal antibody (10/13) were found to be between 1 in 50 and 1 in 500. Binding of these antibodies to immobilized PC or to monoclonal idiotope‐specific antibodies could be inhibited by soluble PC in a solid‐phase radioimmunoassay. Around half the PC‐specific B cell clones were found to also bind 10/13 idiotope‐specific monoclonal antibody, while the rest were either PC specific, but idiotope‐negative or idiotope‐positive, and unable to bind immobilized PC.
Comparison of thymic and peripheral T cell Ly‐2/3 antigens
Authors: Walker Ian D. , Murray Brendan J. , Hogarth P. Mark , Kelso Anne , McKenzie Ian F. C. 
Published: February 2007

AbstractMajor structural differences occur between the thymic and peripheral T cell forms of the Ly‐2/3 antigen. Thymus Ly‐2/3 consists of similar amounts of two types of disulfide‐linked heterodimer, αβ and α′β (Mra = 38000, Mra′ = 35000, Mrβ = 30000). In contrast material from peripheral T cells consists almost exclusively of αβ dimers. The α chains of thymus and peripheral T cells differ also in isoelectric point with the thymic α chain being the more acidic. Based on peptide mapping experiments the α and α′ chains of thymus are likely to be alternatively modified forms of the same polypeptide backbone.Individual T cell clones or T cell tumors propagated in vitro exhibit either a typical thymus or a typical peripheral T cell Ly‐2/3 polypeptide pattern indicating that the synthesis of both α and α′ chains can occur in the same cell. The heterogeneity of thymic Ly‐2/3 can be considerably reduced by removal of sialic acid residues, and after desialylation the α chains of thymus and a cloned cytotoxic T lymphocyte (CTL) line cannot be electrophoretically distinguished. If Ly‐2 structures affected the antigen specificity of CTL, a different structural variant would be expected in individual clones. The electrophoretic identity of desialylated thymus and CTL α chains suggests that Ly‐2 does not exhibit clonal variation in polypeptide structure and, therefore, cannot contribute to antigen specificity.
Synergistic protection by specific antibodies and interferon against infection by Trypanosoma cruzi in vitro
Authors: Plata Fernando , Wietzerbin Juana , Pons Francisco Garcia , Falcoff Ernesto , Eisen Harvey 
Published: February 2007

AbstractTrypanosoma cruzi infects many mammalian cell types in vitro, including fibroblasts and macrophages. We have analyzed and compared the infection of mouse 3T3 fibroblasts and J774 macrophage‐like tumor cells by cloned Y‐A1.2 T. cruzi trypomastigotes. The effects of T. cruzi‐specific antibodies and of interferon (IFN) on infection were considered. Specific antibodies protected 3T3 fibroblasts from infection by T. cruzi, but increased the relative infectivity for J774 cells due to binding of the opsonized parasite to J774 Fc receptors. It was also apparent that IFN‐α,β (produced by fibroblasts) and IFN‐γ (produced by T lymphocytes) activated trypanocidal activities in both 3T3 and J774 cells, although IFN‐γ was 100 to 2000 times more effective than IFN‐α,β on the basis of IFN antiviral units added per culture. When anti‐T. cruzi antibodies and IFN‐α,β or IFN‐γ were used jointly, a synergistic protective effect was observed with both 3T3 fibroblasts and J774 cells. These results suggest that B and T lymphocytes might collaborate in vivo in the protection against T. cruzi infections by the production of anti‐trypomastigote antibodies and IFN‐γ, respectively.
Secretion of a macrophage‐activating factor distinct from interferon‐γ by human T cell clones
Authors: Andrew Peter W. , Rees Ann D. M. , Scoging Anne , Dobson Nicola , Matthews Ruth , Whittall J. Trevor , Coates Anthony R. M. , Lowrie Douglas B. 
Published: February 2007

AbstractSupernatants from clones of human T lymphocytes that were responding to a purified Mycobacterium tuberculosis antigen were able to activate macrophages and macrophage‐like myeloma cells (U937) to release increased amounts of the microbicidal agent hydrogen peroxide. The activity was not neutralized by monoclonal antibody against interferon‐gamma (IFN‐γ), was greater than could be accounted for by the IFN‐γ activity in the supernatants, and was separated from IFN‐γ by high performance liquid chromatography. It is evident that IFN‐γ is not the only macrophage activator released by T lymphocytes responding to microbial antigen, and may not even be the main one to enhance antimicrobial activity in infections such as tuberculosis.
IgG pair formation on one antigenic molecule is the main mechanism of synergy between antibodies in complement‐mediated lysis
Authors: Hughes‐Jones Nevin C. , Gorick Barbara D. , Miller Nigel G. A. , Howard Jonathan C. 
Published: February 2007

AbstractTwo rat IgG2b monoclonal antibodies bound to different epitopes on a single RT1Aa antigen molecule synergize in their induction of complement‐mediated lysis of the red cells. The mechanism of this synergistic action has been investigated by determining the C1q: IgG relationship on red cells using the fluorescence‐activated cell sorter and making use of the considerable variation in antigen density between individual red cells. With a synergistic pair of antibodies, the C1q: IgG ratio was approximately 1 and independent of antibody density per cell, indicating that the antibody molecules are present as closely associated pairs, each pair binding two C1q molecules and thus forming a cyclic tetramer. When one of the antibodies was used alone, the number of C1q molecules bound relative to the amount of antibody was higher than expected from theoretical considerations based on a presumed random distribution of antigen‐antibody complex. This result can be explained if there is some mobility of the complex within the membrane. The interpretation of the results gives strong support to the hypothesis that C1q must bind bivalently to rat IgG2b complexes.
Clonal endurance and clonal burst size: novel indices of helper T cell heterogeneity
Authors: Miller Richard A. 
Published: February 2007

AbstractThis report presents a method for examining the behavior of individual antigen‐responsive helper T cell precursors (pHTL), following their repeated encounter with antigen. In our model system, lymph node cells from mice immunized with keyhole limpet hemocyanin (KLH) are cultured in vitro under limiting dilution conditions, using responder cell doses chosen to ensure that each culture well contains, at the outset, at most a single KLH‐reactive helper T cell precursor. Those wells which in fact did receive a KLH‐reactive pHTL are identified by the accumulation of the helper T cell product, interleukin 3 (IL 3), during a 6‐day culture interval. The lymphocytes generated during this culture interval are washed, divided into replicate aliquots, and then further cultured (with and without additional KLH) to see if the original pHTL has generated cells which are capable of further lymphokine production.Using this approach, we found a surprising amount of variation from clone to clone in two measurements. Clones differed greatly in “endurance”, that is in the ability of progeny cells to continue to secrete IL 3 in the absence of additional antigenic stimulation. Among 148 clones tested, 90 were found not to continue lymphokine secretion in antigen‐free secondary cultures, while IL 3 production among the other 58 clones varied from 1 to 128 arbitrary units. Individual clones also varied greatly with respect to their ability to secrete additional IL 3 in response to additional antigen, and in “burst size”, that is in the number of new, antigen‐responsive helper cell precursors which they can generate during the initial culture interval; 43% of the clones produced no new pHTL, while others produced as many as 800 new pHTL cells in an 8‐day period. Neither measure correlates strongly with the amount of lymphokine originally produced by the initial “parental” pHTL.This method will allow us to examine the factors which influence the allocation of clonal progeny cells into lymphokine producing effectors and antigen‐sensitive “memory” T cells.
Cell surface events which may initiate lysosomal enzyme secretion by human monocytes
Authors: Leoni Patricia , Dean Roger T. 
Published: February 2007

AbstractFreshly isolated and subsequently matured human monocytes secreted lysosomal hexosaminidase in response to exposure to IgG‐Sepharose, but not certain derivatized control Sepharoses. The cells bound selectively to the surface of IgG‐Sepharose (and not the control Sepharoses) but because of the large size of the particles, could not ingest them. Since the soluble IgG was covalently linked to the Sepharose and free soluble IgG was not an inducer of secretion, the secretion was thus induced directly at the cell surface. Zymosan, a yeast cell wall particle which contains a mannan, was also able to induce secretion in the various monocyte stages under study. It could even bind to the cell surface of fresh monocytes which lacked the receptor for mannose‐terminated glycoproteins, and induce secretion in these cells. The mannose receptor appeared as monocytes matured, and the Ir number on the surface was increased by the action of lymphokines. Although zymosan‐induced secretion could be inhibited by mannose and certain other sugars, these seemed to have some complex metabolic effects in human monocytes (which previous work with mouse macrophages has not revealed). Thus, it was not possible to demonstrate whether zymosan could initiate secretion directly by interaction at the monocyte surface mannose glycoprotein receptor.
Helper function of human T cells with different affinity for Helix pomatia A hemagglutinin in a tetanus toxoidinduced B cell differentiation system
Authors: Wikén Margareta , Hellström Ulla , Perlmann Peter 
Published: February 2007

AbstractT cells from human peripheral blood were enriched in T4+ cells by lysis of T8+ cells with the monoclonal antibody OKT8 plus complement. The T4+ subset was separated into 4 fractions differing in avidity for the lectin Helix pomatia A hemagglutinin (HP). The fractions were studied for their capacity to help autologous B cells to differentiate and mature into immunoglobulin (Ig) synthesis and secretion after activation with tetanus toxoid (TT) in vitro. To ensure the antigen specificity of induction, very low doses of TT (1–100 ng/ml) were used for activation of the lymphocytes, all obtained from previously sensitized donors. The T4+ cells with low avidity for HP (fractions HP‐I and HP‐II) exerted little help for B cell differentiation. Removal of these cells enhanced the helper function of the remaining T4+ cells, indicating that fractions HP‐I and HP‐II contained suppressor cells. In contrast, efficient B cell help was provided by T4+ cells with high avidity for HP (fractions HP‐III and HP‐IV). However, these fractions differed in the quality of help provided. Thus, while HP‐III cells induced IgG secretion, HP‐IV cells mainly induced IgM secretion. Moreover, while the Ig secreted after help from HP‐III cells was TT‐specific antibody, the Ig secreted by B cells in the presence of autologous HP‐IV cells was polyclonal, probably reflecting induction of B cells, differing in their responsiveness to signals provided by different types of T cells. The results indicate that T4+ cells vary in their stage of differentiation as seen by differences in expression of the HP marker and that differences in HP‐marker expression appear to be associated with differences in cellular functions.
Effects of μ‐specific antibodies on B cell growth and maturation
Authors: Leanderson Tomas , Forni Luciana 
Published: February 2007

AbstractOver a wide range of concentrations affinity‐purified rabbit anti‐mouse μ chain antibodies, or their F(ab′)2 fragments, inhibit the appearance of immunoglobulin‐secreting cells (plaque‐forming cells; PFC) in lipopolysaccharide‐stimulated murine spleen cell cultures without affecting proliferation. Both IgM and IgG PFC are inhibited although the number of blasts bearing surface IgG remains unaltered. The IgM and IgG PFC response could be reconstituted to normal levels in cell cultures suppressed by μ‐specific antibodies by the addition of supernatants from in vitro propagated helper T cell clones, or from EL4 lymphoma cells induced with phorbol ester. Interleukin 1‐containing P388 supernatant, or recombinant DNA‐derived murine interferon‐γ, did not reconstitute the PFC response in cell cultures suppressed by μ‐specific antibodies, indicating that other factors are responsible for these effects. When spleen cell cultures, pre‐activated with either lipopolysaccharide or monoclonal mouse μ‐specific antibodies coupled to Sepharose, were exposed to EL4 supernatants in the presence of soluble μ‐specific antibodies, maturation to secretion was inhibited while proliferation was not. The implications of these findings on assay systems for B cell growth and maturation factors are discussed.
Frequency analysis of cytolytic T lymphocyte precursors (CTL‐P) generated in vivo during lethal rabies infection of mice. II. Rabies virus genus specificity of CTL‐P
Authors: Reddehase Matthias J. , Cox James H. , Koszinowski Ulrich H. 
Published: February 2007

AbstractCytolytic T lymphocyte precursors (CTL‐P) were sensitized in vivo by intraplantar infection of C57BL/6 mice with a lethal dose of rabies virus, strain ERA (ERA). As a result of sensitization CTL‐P matured to interleukin‐receptive CTL‐P (IL‐CTL‐P) that could be expanded in vitro to Thy‐1+, Lyt‐2+ CTL clones in the presence of IL without subjection to antigen‐driven selection. After infection with ERA, IL‐CTL‐P‐derived CTL lysed fibroblasts infected with rabies virus but not those infected with another rhabdovirus, the vesicular stomatitis virus. These CTL, however, did not discriminate between fibroblasts infected with the serologically closely related laboratory strains of classic rabies virus, ERA and HEP‐Flury, and the serologically distinct rabies‐related African isolate Mokola. This finding implies that in vivo sensitized IL‐CTL‐P recognize common genus‐specific determinants expressed on cells infected with members of the lyssavirus genus.
Macrophage antitumor activity: impaired responsiveness to interferon‐γ of macrophages from genetically defective mice
Authors: Boraschi Diana , Censini Stefano , Tagliabue Aldo 
Published: February 2007

AbstractMacrophages (Mϕ) from the genetically defective mouse strains C3H/HeJ, A/J and P/J were unable to develop high levels of antitumor activities when stimulated either with immune recombinant interferon gamma (IFN‐γ) or with nonimmune IFN‐α and IFN‐β, as compared to Mϕ or normal C3H/HeN mice. IFN‐γ appeared to be an exceptionally good activator of C3H/HeN Mϕ, as it could induce tumoricidal capacities 3000 times more efficiently than nonimmune IFN. The high efficiency of IFN‐γ as Mϕ activator was indeed confirmed on defective Mϕ. In fact, at high doses IFN‐γ could also induce significant levels of both cytolytic and cytostatic activity in Mϕ of A/J and P/J mice, although it could not increase cytotoxic activities of C3H/HeJ Mϕ.
Beneficial effect of cyclosporin A on the lymphocytic choriomeningitis virus infection in mice
Authors: Saron Marie‐Françoise , Shidani Babak , Guillon Jean‐Claude , Truffa‐Bachi Paolo 
Published: February 2007

AbstractThe effect of cyclosporin A on the course of lymphocytic choriomeningitis virus infection in mice was investigated. Evidence is presented that administration of this immunosuppressive drug spares a majority of lethally infected mice. This beneficial effect is different from the one obtained with other treatments leading to the abolition of T cell functions. Surviving animals rapidly eliminate the virus and produce high titers of neutralizing IgG antibodies.
Protection of the classical and alternative complement pathway C3 convertases, stabilized by nephritic factors, from decay by the human C3b receptor
Authors: Fischer Elizabeth , Kazatchkine Michel D. , Mecarelli‐Halbwachs Lise 
Published: February 2007

AbstractFormation and function of the classical (C4b, 2a) and alternative (C3b, Bb) complement pathway C3 convertases are regulated by the intrinsic lability of the enzymes, extrinsic decay by C4bp and H, cleavage of C4b and C3b by I, and by the inhibitory action of the C3b receptor molecule (CR1). Binding of C4 nephritic factor (C4Nef) to C4b and of C3 nephritic factor (C3Nef) to C3b stabilizes the C3 convertases and bypasses inactivation by C4bp, H and/or I. In the present study, binding of C4Nef to the classical C3 convertase was found to prevent decay of C4b, 2a by inputs of CR1 that were at least 15 times the amount of CR1 which inactivated 50% unstabilized classical pathway C3 convertase sites in 2.5 min. CR1 could however inhibit lysis of C4b, 2a(C4Nef)‐bearing cells in a dose‐dependent manner. The latter inhibitory effect was directed at the interaction of C5 with the C5 convertase, most likely at C5 binding to cell‐bound C3b. In an analogous manner to C4Nef in the classical pathway, stabilization of alternative pathway C3b, Bb convertase sites by C3Nef resulted in a relative protection of C3 convertase sites from decay by CR1. Thus, C4Nef and C3Nef can bypass all mechanisms susceptible to regulate function of the classical and alternative pathway C3 convertases. Because CR1 is essential for degradation of C3b bound to immune complexes in whole blood, stabilization of C4b,2a and C3b, Bb by C4Nef and C3Nef may alter in vivo processing of immune complexes in patients with nephritic factors.