bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional differences between B cell‐depletion techniques in removing memory B cells. Relevance to anti‐erythrocyte autoantibody‐specific suppressor cells
Authors: Watt Graham J. , Elson Christopher J. , Greenwood Mark , Miller Peter 
Published: February 2007

AbstractThe efficiency of a number of B cell‐depletion techniques was examined in a functional assay. CBA (Iga) mice were primed with rat erythrocytes and their spleen cells transferred, before and after B cell depletion, to mice of the allotype‐congenic strain Igb. The recipients were challenged with rat erythrocytes and their anti‐erythrocyte autoantibody response was measured together with the donor (Iga) and host (Igb) anti‐rat erythrocyte antibody levels. Transferred unseparated cells suppressed erythrocyte autoantibodies and produced high levels of anti‐rat erythrocyte antibodies. Transfer of panned, rosetted or nylon wool‐passaged cells neither altered donor anti‐rat erythrocyte antibody levels nor abrogated suppression. By contrast, passage of rat erythrocyte‐primed B cells over Ig‐anti‐Ig‐coated beads resulted in removal of donor rat‐primed B cell activity and loss of suppressor cells. The B cell‐depletion techniques were effective at removing B cells as judged by the reduced number of fluoresceinated anti‐Ig‐labeled cells among unbound cells although analysis on a fluorescein‐activated cell sorter revealed that the most effective method was depletion on Ig‐anti‐Ig‐coated beads.B cell depletion by panning removed the capacity of virgin but not primed cells to make adoptive antibody responses after transfer suggesting that the primed cells most efficient in adoptive transfer have a lower density of surface Ig than virgin cells. Treatment of donors with drugs which abrogated transferrable suppression of erythrocyte autoantibodies did not alter donor anti‐rat erythrocyte antibody levels in recipients. It is considered that rat primed B cells are involved in the suppression of erythrocyte autoantibodies by acting as selective antigen‐presenting cells for T suppressor inducer cells, rather than through an anti‐rat erythrocyte antibody feedback mechanism.
Role of the Ly 1 antigen in interleukin 1‐induced thymocyte activation
Authors: Lögaberg Lennart , Shevach Ethan M. 
Published: February 2007

AbstractInterleukin 1 (ILI), but not IL2‐induced thymocyte proliferation was augmented by monoclonal antibodies (mAb) against the Ly 1 antigen. The anti‐Ly 1 mAb could also co‐stimulate thymocytes with phytohemagglutinin (PHA) alone, mimicking the effect of IL1. Moreover, overnight culture with PHA of thymocytes, but not of spleen T lymphocytes led to selectively enhanced expression of the Ly l antigen on the cell surface. Similar data were generated at the clonal level. Thus, a thymocyte hybridoma (22A6) could be stimulated to release IL2 in response to PHA plus IL 1, but also to PHA plus anti‐Ly 1 mAb. In addition, 22A6 exhibited enhanced cell surface expression of the Ly l antigen after overnight culture with PHA. These data suggest a critical role for the Ly1 antigen in thymocyte proliferation, perhaps by serving as an IL 1‐receptor.
Antigen‐specific major histocompatibility complex‐restricted helper T cell clones are sufficient to induce unprimed B cells to switch and to secrete IgG and IgA in a primary in vitro polyclonal response
Authors: Leclercq Lise , Chastagnier Patricia , Mishal Zohair , Bismuth Georges , Thèze Jacques 
Published: February 2007

AbstractTo investigate the role of helper T (Th) cells in the regulation of the production of the various immunoglobulin (Ig) classes and subclasses, we have used poly (Glu60Ala30Tyr10) (GAT)‐specific, major histocompatibility‐complex‐restricted Thcell clones to stimulate unprimed B cells. The T cells used in these studies were Thy‐1+, Lyt‐l+, Lyt‐2− and lacked Fc receptor for IgM, IgG and IgA, and the unprimed splenic B cells were selected by the fluorescence‐activated cell sorter for their lack of expression of surface (s)IgG and by panning for their lack of expression of sIgA. We have taken advantage of the ability of some antigen‐specific major histocompatibility complex (MHC)‐restricted Th cell clones to polyclonally activate unprimed B cells in vitro in the presence of high doses of antigen. We have shown that under these conditions, an antigen‐specific MHC‐restricted Th cell clone is sufficient to induce the switch of sIgG− sIgA− unprimed B cells to IgG and IgA, as well as the expansion of these cells and their differentiation into IgG and IgA‐secreting cells. Isotype‐specific Th cells thus do not seem to be an absolute requirement for the production of the various IgG subclasses and of IgA.
A subset of OKT4+ peripheral T cells can generate colonies containing mixed progeny with OKT4+ helper and OKT8+ suppressor cells
Authors: Farcet Jean Pierre , Gourdin Marie‐Françoise , Calvo Charles , Oudrhiri Nouflssa , Divine Marine , Bouguet Jacqueline , Fradelizzi Didier , Senik Anna , Reyes Felix 
Published: February 2007

AbstractThe membrane phenotype of human T cell colony progenitors and that of their clonal progeny was studied for expression of the T4 and T8 determinants. Using clonal culture conditions, the colonies were grown in semi‐solid agar medium from peripheral blood cells. Clonality was assessed using the glucose‐6‐phosphate‐dehydrogenase isoenzyme marker. Combination of this marker with the culture of sorted cell fractions allowed us to ascribe the colony progenitors to a subset of OKT4+lymphocytes. The progeny consisted of the mixture of single OKT4+, single OKT8+and double OKT4+8+ cells, as determined by double staining. Double staining was performed on mass‐harvested colony cells and on individual colonies expanded in liquid culture with fresh interleukin 2. Expression of the OKT8 positivity on colony cells deriving from OKT4+ progenitors required an interaction with radioresistant OKT8+ cells that were co‐cultured with these progenitors. Furthermore, the functional capacities of the cell progeny were assayed on the pokeweed mitogen‐driven immunoglobulin production by B cells. It was found that OKT4T colony cells were helper whereas OKT8+ colony cells were suppressor cells. It is concluded that a subset of OKT4+ peripheral blood T lymphocytes can generate colonies containing both helper OKT4+ cells and suppressor OKT8+ cells.
Inhibition of experimental autoimmune uveoretinitis in rats by S‐antigen‐specific monoclonal antibodies
Authors: de Kozak Yvonne , Mirshahi Massoud , Boucheix Claude , Faure Jean‐Pierre 
Published: February 2007

AbstractMouse monoclonal antibodies (mAb), of either IgG2a or IgG2b isotypes, specific for the retinal S‐autoantigen (S‐Ag) or a pool of rat anti‐S‐Ag sera prevented experimental autoimmune uveoretinitis in Lewis rats when injected i.p. at the time of immunization. Control mAb of the same isotypes, irrelevant to S‐Ag, had no inhibitory effect. The humoral response to S‐Ag, as studied by enzyme‐linked immunosorbent assay using a mouse mAb specific for rat kappa chain, was moderately but significantly reduced in suppressed animals. The rapid disappearance of the injected mAb from rat sera, as measured using a rat mAb specific for mouse kappa chain, could be explained by its complexing with either autologous antigen released from the retina at the site of inflammation, or anti‐idiotypic antibodies.
Search for class II major histocompatibility complex molecular involvement in the response of Lyt‐2+cytotoxic T lymphocyte precursors to alloantigen
Authors: Romani Luigina , Mage Michael G. 
Published: February 2007

AbstractA possible requirement for class II major histocompatibility complex (Ia) molecules in the initial activation of cytotoxic T lymphocyte precursors (CTLp) for allocytotoxic responses was investigated. To avoid possible interaction with other alloreactive cell types, a highly purified population of Lyt‐2+ splenocytes was used as a source of CTLp. In the light of preliminary results indicating that Lyt‐2+ CTLp, even in the presence of interleukin 2 (IL2), could best be triggered into mature CTL in vitro by cells known to be Ia+, we examined whether an interaction of CTLp with Ia antigens (either on syngeneic accessory cells or on allogeneic stimulators) played a role in the development of allocytotoxicity. Results from experiments done with C57BL/6 Lyt‐2+splenocytes co‐cultured with P815 stimulator cells and IL2 showed that the early activation of CTLp was independent of Ia+ syngeneic accessory cells: (a) flow microfluorometry analysis of the responder population at the beginning or after 1 or 3 days of co‐culture did not reveal the presence of Ia+ cells; (b) procedures for removal of residual Ia+ cells or of dendritic cells from the responder population before co‐culture did not affect the development of cytotoxicity; (c) co‐culture with monoclonal antibodies against syngeneic Iab antigens did not inhibit the CTLp activation. By comparing an Ia+ P815 tumor line with its Ia− clone as allogeneic stimulator cells, it was found that the CTLp activation was also independent of Ia alloantigen on the stimulator cells. The response against both the Ia+ and the Ia− stimulator cell types was not inhibited by monoclonal anti‐L3T4 present in the co‐culture, indicating that these responses were not affected by residual L3T4 helper cells.
Isolation and characterization of Abelson murine leukemia virus‐transformed mast cell lines from midgestation embryonic placenta
Authors: Siegel Michael L. , Horwitz Randy , Morris Timothy D. , Di Venere Raina M. , Siden Edward J. 
Published: February 2007

AbstractAbelson murine leukemia virus was used to transform cells of the midgestation embryonic placenta. The frequency of transformed foci in semisolid agarose was highest when cells were isolated at 10 days of gestation and cell lines could be established in liquid culture. The continuous cell lines express characteristics of cultured mast cells, including surface antigens which are shared with lymphocytes and mono‐ nuclear phagocytes. These results imply a relationship between the transforming gene product and the mast cell growth factor interleukin 3.
A neomycin‐resistant cell line for improved production of monoclonal antibodies to cell surface antigens
Authors: van Snick Jacques , de Plaen Etienne , Boon Thierry 
Published: February 2007

AbstractOvergrowth of hybridomas by proliferating spleen T cells often hinders the production of monoclonal antibodies to certain antigens. To overcome this problem we derived neomycin‐resistant fusion partner SP2neoR.l by transfection of SP2/0‐Agl4 cells with plasmid pSVTK neo beta. Hybridomas obtained with SP2 neoR.1 grew optimally in the presence of the neomycin analog G418 at concentrations which blocked the proliferative response of T cells to mitogenic stimuli. The advantage of using SP2 neoR.1 and G418 under conditions where spleen cell proliferation occurs after fusion was demonstrated with hybridomas derived from a rat immunized with mouse helper T cell lines.
Development of T cell clones reactive to two defined restriction elements in conjunction with two defined epitopes of antigen
Authors: Spaeth Eberhard , Rüde Erwin 
Published: February 2007

AbstractA previously described pig insulin (Pl)‐specific T cell line of (B10 × B10.BR)F1 origin was assayed for its reactivity with species variants of insulin in the presence of antigenpresenting cells (APC) of various H‐2 haplotypes. In addition to its reactivity with PI and bovine insulin (BI) in the context of syngeneic F1 (H‐2bxk)‐APC, a weak crossreactivity was observed with parental B10 (H‐2b)‐APC and BI but not PI. The crossreactive cells could be selected out by several restimulations with the combination of BI and B10‐APC. From the resulting, strongly cross‐reactive T cell line several interleukin 2‐dependent sublines were developed which did not require antigen‐specific restimulations for further propagation. All such sublines had retained the original cross‐reactivity with BI and B10‐APC but showed significant differences in their fine specificity patterns, which indicates that each subline represents a clonal population. One of the sublines was cloned by limiting dilution at one cell/culture with a cloning efficiency of 76%. Five of the clones that were tested for reactivity had the same cross‐reactivity as the original subline and upon recloning at 0.1 cells/culture the pattern again remained unchanged. From an analysis of the two antigen combinations (PI/F1 and BI/B10) it can be concluded that single cells can react with different restriction elements in the context of distinct epitopes of insulin. The implications of this finding for the mechanism of T cell recognition are discussed and a model for the function of major histocompatibility complex molecules in T cell recognition is proposed.
Interleukin 2 mRNA induction in human lymphocytes: analysis of the synergistic effect of a calcium ionophore A23187 and a phorbol ester
Authors: Yamamoto Yusei , Ohmura Takafumi , Fujimoto Kouji , Onoue Kaoru 
Published: February 2007

AbstractInduction of interleukin 2 (IL2) mRNA in human tonsillar lymphocytes under various conditions was examined by cytoplasmic dot hybridization using a 32P‐labeled IL 2 cDNA probe to study the signal transduction mechanisms which lead to IL2 gene expression. A tumor‐promoting phorbol ester, 12‐O‐tetradecanoyl‐phorbol 13‐ace‐tate (TPA), acted synergistically with a Ca2+ ionophore A23187 or phytohemaggluti‐nin (PHA) to induce a high level of IL2 mRNA in lymphocytes, whereas each of them by itself could not induce the mRNA production. In two‐step culture experiments the lymphocytes pulse‐incubated with TPA for 1 h (the first culture) could efficiently initiate IL2 mRNA production by subsequent culture with A23187 or PHA (the second culture). Results obtained by removal of extracellular Ca2+ from either the first or second culture revealed that Ca2+ was not necessarily required during the first culture with TPA, but it is essential in the second culture with A23187 or PHA, regardless of the presence or absence of Ca2+ in the first culture. A reagent known to be a calmodulin antagonist, N‐(6‐aminohexyl)‐5‐chloro‐l‐naphthalenesulfonamide (W‐7), almost completely inhibited the IL2 mRNA induction in A23187‐TPA‐stimu‐lated lymphocytes at a concentration of 25 μM, whereas N‐(6‐aminohexyl)‐l‐naph‐thalenesulfonamide that has much lower affinity for calmodulin than W‐7 did not inhibit at this concentration. The IL2 mRNA induction was also blocked by the addition of 50 UM of 8‐(N, N‐diethylamino)‐octyl‐3,4,5‐trimethoxybenzoate hydro‐ chloride which is known to block the release of Ca2+ from intracellular storage sites. These results show that mobilization of Ca2+ and the calmodulin‐dependent regulatory system appear to work synergistically with TPA which probably activates protein kinase C in the pathway to IL2 gene expression.
Proliferative responses of circulating human NK cells: delineation of a unique pathway involving both direct and helper signals
Authors: Ythier Arnaucl , Delmon Laurence , Reinherz Ellis , Nowill Alexandra , Moingeon Philippe , Mishal Zohair , Bohuon Claude , Hercend Thierry 
Published: February 2007

AbstractThe present studies were performed to investigate mechanisms of human natural killer (NK) cell activation. NK‐active cells were purified out of heterogeneous large granular lymphocytes (LGL)‐enriched suspensions using a “pan NK”‐specific monoclonal antibody termed anti‐NKHlA. It was found that treatment of NKHlA+‐sorted cells by T lymphocyte mitogens such as phytohemagglutinin (PHA) or anti‐TH2 plus anti‐Tll3 did not induce proliferative responses. In fact, there was no measurable interleukin 2 (IL 2) secretion and no significant increase in IL 2 susceptibility following incubation with either PHA or anti‐TH2 plus anti‐T113. However, as opposed to small resting T lymphocytes, NKH1A+ cells moderately proliferated in the presence of IL2. This IL 2‐dependent proliferation was dramatically increased after interaction between NK‐active lymphocytes and certain hematopoietic cell lines such as K562 or EBV‐transformed lymphoblastoid cell lines.These studies indicate that unique activation mechanisms can be identified when NK lymphocytes are purified out of LGL‐enriched fractions. The NK activation pathway delineated here appears essentially distinct from those described for T lymphocytes. Indeed the nature of the NK cell/inducing cell interaction is unknown and triggering cannot be related, for example, to a conventional allogeneic effect mediated through membrane exposure of class I or class II major histocompatibility complex gene products. Moreover, these interactions do not lead to the development of autocrine responses. Together the present results support the view that direct signals can preac‐tivate NK cells but are not sufficient to trigger proliferation which must therefore be regulated by helper populations.
An inherited deficiency of the third component of complement, C3, in guinea pigs
Authors: Burger Reinhard , Gordon John , Stevenson George , Ramadori Guliano , Zanker Bernd , Hadding Ulrich , Bitter‐Suermann Dieter 
Published: February 2007

AbstractHereditary deficiency of the third component of complement, C3, is found very seldom in the human. C3 deficiency is associated with severe bacterial infections revealing the central role of C3 in complement activation via the classical or alternative pathway. We describe a new hereditary C3 deficiency in strain 2 guinea pigs. Serum from these animals had a markedly reduced lytic activity in a standard assay for complement‐dependent, antibody‐mediated cytotoxicity. In functional assays of individual components, the hemolytic activity of the components C4, C2, C5 and of factors B, D and H was in the normal range. The functional C3 titer, and similarly C3 antigenic activity in the serum of these C3‐deficient animals (C3D) was on average only 5.7% of normal activity. Typing the animals with alloantisera or monoclonal antibodies to guinea pig Ia‐antigens revealed that the C3D animals had the major histocompatibility complex‐haplotype of inbred strain 2 guinea pigs (B.1, Ia. 2,4). The C3 defect is not linked to the major histocompatibility complex and, in addition, is not linked to a C3a receptor deficiency. Macrophages and hepatocytes of the C3D animals have an unimpaired capacity for synthesis and secretion of C3 as measured by enzyme‐linked immunosorbent assay. There was no indication for hypercatabolism of normal C3 by the animals as shown by plasma clearance of 125I‐radiolabeled C3. Thrombocytes of the C3D animals responded normally to stimulation with purified C3a in an ATP‐release assay without an indication for a desensitization in vivo. Possibly the fault resides in an enhanced susceptibility of their own C3 to proteolysis. However, C3 partially purified from the plasma of the C3D animals or secreted by hepatocytes exhibited no obvious structural differences to purified normal C3 in sodium dodecyl sulfate‐polyacrylamide gel electrophoresis or in immunoblotting. The C3D serum had a reduced bactericidal activity compared to normal or to C4‐deficient serum. Nevertheless, the animals are apparently healthy without an indication for increased frequency of bacterial infections. These guinea pigs provide an unique model for analysis of the biological functions of C3 in vivo and in vitro without the need for artificial C3‐depletion procedures with all their known and unknown side‐effects.
Human monocyte cell line (U937) releases suppressive IgG‐binding factor(s)
Authors: Calvo Charles Félix , Watanabe Shinichiro , Mètivier Didier , Senik Anna 
Published: February 2007

AbstractFcγ receptor‐bearing U937 cells, when incubated in serum‐free buffer, were found to release spontaneously a suppressor material for pokeweed mitogen‐drigen IgG synthesis which could be retained on Sepharose 4B‐IgG immunosorbents. Immunosorbents coupled with IgM or F(ab′)2 fragments of IgG were unable to retain the inhibitory activity of U937‐derived material, suggesting a binding specificity for the Fcγ fragment of IgG. This suppressor material corresponds therefore by definition to an IgG‐binding factor (IgG‐BF). The mechanism for in vitro suppression of the antibody response by U937‐derived IgG‐BF was investigated. It did not interfere with cell proliferation and displayed maximum effect when added at day 3 of the culture period. Tested for its effect on IgG, IgM and IgA synthesis, IgG‐BF suppressed antibody production following a pattern specific for IgG. Finally gel filtration of the suppressor material gave rise to two peaks of inhibitory activity with an apparent molecular mass comprised between 30 to 40 kDa and 60 to 73 kDa, respectively.
The level of λ1 light chain expression in the mouse reflects the probability of rearrangement of the relevant gene
Authors: Primi Daniele , Levi‐Strauss Matthieu , Cazenave Pierre‐André 
Published: February 2007

AbstractThe predominance of x over λ light chain expression in mice can either reflect the probability of rearrangement of the relevant locus or be the result of antigen‐driven clonal expansion. To discriminate between these two possibilities we determined, by limiting dilution analysis, the frequencies of x‐ and λ‐producing cells in B lymphocytes generated in vitro from bone marrow pre‐B cells. The frequencies obtained in these cultures are not significantly different from those obtained with mature spleen cells. In addition, Southern blot analysis of bone marrow‐derived and splenic cell DNA revealed that in both populations the extent of B lymphocytes having undergone λ1 gene rearrangement does not exceed 4%. These results, therefore, establish that in the mouse the low level of λ light chain expression directly reflects the probability of rearrangement of the relevant locus.
Activation and proliferation signals in mouse B cells VIII. Induction of DNA synthesis in B cells by a combination of calcium ionophores and phorbol myristate acetate
Authors: Klaus Gerry G. B. , O'Garra Anne , Bijsterbosch Martin K. , Holman Mary 
Published: February 2007

AbstractMouse B cells cultured with either phorbol myristate acetate (PMA), or with Ca2+ ionophores enter a transitional activated state, between quiescence (G0) and G1, but do not synthesize DNA. It is shown here that the combination of PMA plus the ionophore ionomycin induces resting B cells to synthesize DNA, but not to secrete antibody. B cells from CBA/N mice carrying the xid defect, and those from the lipopolysaccharide‐unresponsive C3H/HeJ strain also respond to this combination. Suboptimal doses of the two stimuli synergize with B cell‐stimulating factor 1 in promoting proliferation of resting B cells, but the co‐mitogen does not substitute for type II B cell growth factor in the BCL1 lymphoma. Furthermore, (as predicted) the combination of these two agents does not induce the breakdown of inositol phospholipids in B cells. These data are consistent with the hypothesis that elevation of intracellular Ca2+ (by the ionophore), plus activation of protein kinase C (by PMA) leads to DNA synthesis in B cells. The combination of Ca2+ ionophore and PMA thus appears to essentially mimic the biochemical effects of ligation of surface immunoglobulin receptors on B cells, by providing the two second messengers normally emanating from the receptor‐mediated breakdown of polyphosphoinositides.