bluuebunny/crossref_metadata_2025_split huggingface dataset:
Identification and characterization of rat T cell subpopulations expressing T cell receptors α/β and γ/δ
Authors: Lawetzky Alexandra , Tiefenthaler Georg , Kubo Ralph , Hünig Thomas 
Published: March 2007

AbstractPeripheral lymphoid organs of the rat were investigated for the presence of lymphocytes that expressed the pan‐T cell markers CD5 and OX‐52 but not the T cell receptor (TcR) α/β. Two such populations were identified: 2% to 4% of lymphocytes in adult spleen, lymph nodes and peripheral blood are CD5+ TcR α/β− and express the OX‐52 antigen at the same density as TcR α/β+ T‐cells. About 90% of these cells are CD8+. A second population is CD5−, CD8+ and OX‐52low. Radioimmunoprecipitation from digitonin lysates of surface‐labeled cells with an anti‐CD3 antiserum showed that the CD5+, but not the CD5− population of TcR α/β− cells expresses a CD3‐associated disulfide‐linked cell surface molecule of about 100 kDa apparent mol. mass. Upon reduction, one major band, migrating with 48 kDa was observed. A band of the same size was obtained with an anti‐human δ chain peptide antiserum, indicating that the CD3‐associated non‐TcR α/β molecule is the rat TcR α/δ. Functional assays showed that most, if not all natural killer (NK) cell activity is present in the CD5−‐OX‐52low population. Reactivity to foreign major histocompatibility complex (MHC) antigens in mixed lymphocyte reaction was exclusively found in TcR α/β+ splenic T cells. It is concluded that rat α/δ T cells in the spleen do not contain a high frequency of cells with specificity for foreign MHC antigens. The seeding of the periphery with α/β and the presumptive α/δ T cells was followed from birth. Most prominently in the spleen, α/β T cells reached adult levels much later than α/δ T cells. Taken together, these findings demonstrate the expression of the TcR α/δ on a minor population of peripheral rat T cells with the predominant phenotype CD4−CD8+ that has no NK cell activity when freshly isolated and does not contain a high frequency of alloreactive cells.
Reversal of autoimmune encephalomyelitis by membranes presenting myelin basic protein‐associated class II MHC molecule as an approach to immunotherapy of organ‐specific autoimmune diseases
Authors: Ben‐Nun Avraham , Yossefi Sara 
Published: March 2007

AbstractExperimental autoimmune encephalomyelitis (EAE), a well‐accepted experimental model for multiple sclerosis in humans, is a paralytic disease mediated by CD4+ T cells specific for myelin basic protein (MBP). Several approaches to immune‐specific therapy of EAE as a model for other organ‐specific autoimmune diseases have previously been reported. We now show that macrophages (MΦ) or B cells, as antigen‐presenting cells, when pulsed with MBP and intraperitoneally (but not intravenously) inoculated after the encephalitogenic challenge, are highly effective in blocking the development of EAE. Moreover, MΦ pulsed with an organ tissue homogenate, mouse spinal cord homogenate, can also present the relevant target antigen, MBP, and are as effective as MBP‐pulsed MΦ in blocking the development of EAE. This capacity of the MΦ to identify and present the relevant target antigen indicates that this approach is also applicable to organ‐specific autoimmune diseases other than EAE, regardless of how much is known about their etiological agent or specific target antigen. Nonviable glutaraldehyde‐fixed MBP‐pulsed MΦ or membranes derived from MBP‐pulsed MΦ retain their capacity to block the development of EAE.
Restricted utilization of VH and DH genes in leukemic rabbit B cells
Authors: Becker Robert S. , Suter Mark , Knight Katherine L. 
Published: March 2007

AbstractPolyclonal B cell leukemias have been generated in 17‐ to 20‐day old Eμ‐myc transgenic rabbits. To analyze the repertoire of VH genes utilized in early B cells, eight VDJ genes were cloned from these leukemic cells. The nucleotide sequences of these genes indicated that seven of the eight VDJ genes encoded prototype VHal, VHa2 or VHa3 allotypes. The two VDJ genes encoding VHa1 molecules had VH segments with identical nucleotide sequences; similarly, the VH segments of the four VDJ genes encoding VHa2 molecules were identical, with the exception of a single base pair. These data suggest that a limited repertoire of VH genes were utilized in the generation of these VDJ genes. The DH segments of these genes were limited to two DH families, D1 and D2, indicating that a restricted repertoire of DH genes also had been utilized. Since these leukemic cells probably developed early in ontogeny, we suggest that this restricted utilization of VH and DH genes is representative of B cells from developmentally immature rabbits.
Cholera holotoxin and its B subunit enhance Peyer's patch B cell responses induced by orally administered influenza virus: Disproportionate cholera toxin enhancement of the IgA B cell response
Authors: Chen Ker‐Sang , Strober Warren 
Published: March 2007

AbstractIn these studies we analyzed the adjuvant effect of cholera holotoxin or cholera toxin (CT) B subunit on the B cell response to mucosal antigens. Purified Peyer's patch B cells obtained from mice at varying periods of time after oral administration of inactivated influenza virus, with or without a CT preparation, were stimulated in vitro in the absence or presence of various lymphokines. Responses were measured by an antigen‐and isotype‐specific ELISPOT assay. In this system cultures containing a combination of lymphokines [interleukin 5 (IL 5), interferon‐γ (IFN‐γ), IL 4] gave comparable responses to those containing T cells from immunized mice or supernatant of concanavalin A‐stimulated T cells and therefore were assumed to express optimum or near optimum B cell responses. Administration of a CT preparation along with influenza virus increased the number of B cells producing anti‐influenza antibodies of both the IgM and IgA isotypes, with the effect on the IgA response at least threefold greater than the effect on the IgM response. These results thus indicate that CT preparations enhance the memory B cells response in Peyer's patches and, in addition, suggest that CT enhances isotype switching. In this antigen‐specific B cell system IL 4 augmented responses in cultures containing IL 5 but not IFN‐γ; in addition, IL 5 and IFN‐γ acted in an additive fashion. Thus, these findings suggest that the effects of IL 5 and IFN‐γ are at least in part, mediated via different cellular differentiation pathways.
Murine thymocytes possess specific cell surface‐associated exoaminopeptidase activities: Preferential expression by immature CD4−CD8− subpopulation
Authors: Bauvois Brigitte 
Published: March 2007

AbstractMurine thymocytes are shown to possess at least three well‐defined exo‐N‐aminopeptidase activities on their surface. One of them cleaves the prolyl bond in the synthetic dipeptide nitroanilide Gly‐Pro‐pNA (Km 0.95 mM and Vmax 8 nmol/h at pH 7.4 and 37°C) and is specifically inhibited by phenylmethane sulfonyl fluoride, diprotin A, Gly‐Pro‐Ala and Gly‐Pro‐Gly‐Gly. These data further support identification of this enzyme with a serine exopeptidase dipeptidyl peptidase IV (DPP IV), previously reported to be specific for collagen. The two other forms of N‐exopeptidase activities are detected when Ala‐pNA and Leu‐pNA are used as substrates. Leu‐aminopeptidase activity (Km 1.4 mM, Vmax 15 nmo/h) and Ala‐aminopeptidase activity (Km 4.0 mM, Vmax 20 nmo/h) are inhibited by inhibitors for thiol‐ and trypsin‐like proteinases, i.e. tosyl lysyl chloromethyl ketone, leupeptin and N‐ethylmaleimide. Addition inhibition of Leu‐aminopeptidase activity by pepstatin, a known inhibitor of carboxyl proteases, suggests that aminopeptidase activity detected with Leu‐pNA is different in part from Ala‐aminopeptidase activity. Among the various lymphoid cell populations tested, the three aminopeptidase activities are increased by three‐ to fourfold in the immature CD4−CD8− thymocyte subset as well as in the thymoma BW5147. In contrast, cortisone‐resistant thymocytes, lymph node and spleen cells exhibit levels of activities almost similar to that of unfractionated thymocytes. During ontogeny, the levels of these activities are increased four‐ to sevenfold on fetal thymocytes (from days 14 to 16). Finally, when thymocytes or spleen cells are cultured with a mitogenic concentration of concanavalin A, their proliferative responses are correlated with an enhancement of the aminopeptidase activities (1.3‐ to 5‐fold). From these results, a correlation between the presence of these peptidases on the cell surface of immature and mature lymphoid cells and biological responsivenesses is suggested.
Specific deletion of the J‐Cδ locus in murine α/β T cell clones and studies using transgenic mice
Authors: Ohashi Pamela S. , Wallace Valerie A. , Broughton Heather , Ohashi Cara T. , Ferrick David A. , Jost Veronica , Mak Tak W. , Hengartner Hans , Pircher Hanspeter 
Published: March 2007

AbstractA deletion event in the T cell receptor (TcR) δ locus has been characterized in a panel of mouse α/β cytotoxic T lymphocyte (CTL) clones. Data presented here shows that Jδ1, Jδ2 and Cδ are absent from functional CTL clones while a germ‐line Dδ1 fragment is retained, thus suggesting a specific deletion of this region.We have investigated the possible significance of the J‐Cδ deletion by generating T cell lines from TcR α/β transgenic mice. Unlike control T cell lines which included a T cell line derived from a β transgenic mouse, the lines expressing the transgenic α/β heterodimer have not deleted the Cδ region. This strongly suggests that the J‐Cδ deletion event is not responsible for directing T cells to the α/β lineage, but rather is involved in the rearrangement or transcriptional activity of the α locus. In addition, to ensure that the α/β transgene does not have any inhibitory affects on the rearrangement of the δ loci in general, the γ/δ expressing dendritic epithelial Tcell (DETC) population was examined in TcR α/β transgenic mice and alterations in this T cell subset were not found. This finding that normal γ/δ DETC cells are present in α/β transgenic mice, together with the data showing that the Dδ1 region remains in an unrearranged germ‐line configuration in functional α/β CTL, suggests that commitment to the α/β or γ/δ lineage is predetermined at a particular stage in early T cell ontogeny.
Intact, 45‐kDa (membrane) form of CD23 is consistently mitogenic for normal and transformed B lymphoblasts
Authors: Cairns Jennifer A. , Gordon John 
Published: March 2007

AbstractWhen isolated from lysates of the RPMI 8866 B lymphoblastoid cell line, the CD23 antigen was found to be present be in two forms corresponding to the intact 45‐kDa membrane species and to a 25‐kDa product that is more usually found as a released fragment in the extracellular medium. By contrast with preparations of extracellular species of CD23 which were seen to be variable in their biological activity, cell‐associated CD23 was consistently mitogenic both for autogenous transformed B lymphoblasts and for pre‐activated normal B cells. Addition to the normal cocktail of protease inhibitors of Nα‐tosyl‐L‐lysine chloromethylketone (TLCK), which has selectivity for trypsin‐like serine proteases, resulted in preparations of CD23 from RPMI 8866 cell lysates that were exclusively in the 45‐kDa intact form; such material retained full and reliable activity in the biological assays. The implications of these observations for the autocrine control of B lymphocyte growth are discussed.
Interleukin 4 receptors on normal human B lymphocytes: Characterization and regulation
Authors: Zuber Caroline E. , Galizzi Jean‐Pierre , Vallé Alain , Howard Nobuyuki , Howard Maureen , Banchereau Jacques 
Published: March 2007

AbstractHuman interleukin 4 (IL 4) up‐regulates the expression of CD23 on both resting and “in vivo” activated B cells but induces proliferation and/or differentiation only on “in vitro” activated B lymphocytes. Resting B cells express 360 high‐affinity IL 4 receptors (R) per cell (Kd = 25–75 pM). Activation of resting B cells with anti‐IgM antibody or Staphylococcus aureus Cowan I (SAC) results in a two‐to‐threefold increase of IL 4R number without alteration of IL 4R affinity for IL 4. Flow cytometric analysis of biotinylated IL 4 binding shows that IL 4R expression is up‐regulated on virtually all anti‐IgM‐stimulated B cells, but only on a subpopulation of larger cells among SAC‐activated B lymphocytes. Culturing cells for 40 h with optimal concentrations of IL 4 does not significantly affect IL 4R levels on resting and anti‐IgM‐preactivated B lymphocytes but triples IL 4R levels on SAC‐preactivated B cells. Removal of IL 4 from cell cultures results in a two‐to‐fourfold increase of IL 4R levels 2 h later, suggesting an increase in IL 4R turnover. Resting and activated B cells degrade 1251‐labeled IL 4 at 37 °C. Sodium dodecyl sulfate‐polyacrylamide gel electrophoretic analysis of IL 4 binding molecules on resting, “in vivo” activated and anti‐IgM‐activated B cells reveals the same three species of 130, 80‐75, 70‐65 kDa. Thus, IL 4 displays its different biological activities on resting and activated B cells through IL 4R of the same affinity, gross biochemical structure and ability to mediate IL 4 degradation.
Fine manipulation of antibody affinity for synthetic epitopes by altering peptide structure: Antibody binding to looped peptides
Authors: Jemmerson Ronald , Hutchinson Robert M. 
Published: March 2007

AbstractLinear peptides weakly imitate antibody binding sites on globular proteins when the peptides are shown to be effective at all. As a step toward enhancing the ability of peptides to mimic epitopes, we have examined the effects of various alterations in peptide structure on antibody binding. Synthetic peptides containing the core amino acid sequence of residues 41 to 48 from horse cytochrome c were examined for their ability to bind antibodies elicited against the 41–48 peptide coupled to bovine serum albumin (BSA). Since residues 41–48 in native cytochrome c are part of an omega loop, in some peptides cysteines were incorporated for intrachain disulfide bonding to stabilize loop structure. In additional cases, glycine was incorporated as a spacer between the natural sequence and the cysteine residues with the intent of relaxing loop structure slightly. Eleven analogues containing the 41–48 sequence were tested. These included native cytochrome c and the 1‐80 and 1‐65 cyanogen bromide‐cleaved fragments. The native protein did not bind the anti‐41–48 antibodies. The other analogues differed by over three orders of magnitude in their binding. The affinity of binding was inversely related to the extent of predicted loop structure indicating that the antibodies were elicited against the 41–48 sequence in a more unfolded conformation despite the Pro Gly sequence at positions 44 and 45 that generally favors a β turn. Surprisingly, the immunizing peptide, containing residues 41–48 only, was the poorest binding peptide. The relative impotence of 41–48 was shown to be largely due to differences at the amino terminus between the free and BSA‐coupled peptides as the antibodies were elicited against the latter. The distinctions among the synthetic peptides containing the 41–48 sequence show the exquisite sensitivity of antibody binding to amino acid changes that may occur outside of an epitope and suggest modifications in peptide structure at the periphery of an epitope that can lead to desired changes in antibody affinity.
Type 6 and 19 pneumococcal polysaccharides coupled to erythrocytes elicit pneumococcal cell wall‐specific primary IgM responses and capsular polysaccharide‐specific secondary IgG responses
Authors: Milligan Gregg N. , Fairchild Robert L. , Sterner Kay E. , Braley‐Mullen Helen 
Published: March 2007

AbstractPrevious results have shown that the primary murine antibody responses to vaccine preparations of type 6 (S6; Danish type 6A) or type 19 (S19; Danish type 19F) pneumococcal capsular polysaccharides consist entirely of IgM antipneumococcal cell wall carbohydrate (PnC)‐specific antibodies. No capsular polysaccharide‐specific IgM antibodies were detectable by plaque‐forming cell or enzyme‐linked immunosorbent assay techniques. In this report, antibodies specific for S6 and S19 capsular polysaccharides were induced in secondary responses to chicken erythrocyte (CRBC) conjugates of S6 and S19. Essentially all detectable IgG produced in the secondary response was capsular polysaccharide specific and included all subclasses of IgG. In contrast, all detectable IgM produced in the primary response to S6‐CRBC and S19‐CRBC, and the IgM produced in the secondary response to S6‐CRBC was not capsular polysaccharide specific since it reacted with PnC. Thus, there is a major change in the specificity of the primary IgM response compared to the secondary IgG response of mice immunized with S6‐CRBC or S19‐CRBC. Injection of PnC or any PnC‐containing polysaccharide prior to immunization with S6‐CRBC or S19‐CRBC resulted in suppression of the primary IgM response. In contrast, only the capsular polysaccharide used in the immunizing polysaccharide‐erythrocyte conjugate suppressed induction of the capsular polysaccharide‐specific secondary IgG response. These results suggest that S6 and S19 capsular polysaccharidespecific IgG‐producing memory B cells derive from capsular polysaccharidespecific precursors which do not produce detectable antibody after primary immunization.
Synergy of tumor necrosis factor with protein kinase C activators on T cell activation
Authors: Angeles Muñoz‐Fernández M. , Pimentel‐Muiños Felipe X. , Alonso Miguel A. , Campanero Miguel , Sánchez‐Madrid Francisco , Silva August , Alonso José Luis , Fresno Manuel 
Published: March 2007

AbstractThe ability of tumor necrosis factor (TNF)‐α to activate T lymphocytes in combination with other stimuli has been studied. TNF was strongly co‐mitogenic with low doses of anti‐CD3 antibodies or phorbol esters (those which are strong activators of protein kinase C, PKC) but poorly with phytohemagglutinin or concanavalin A. No synergism was seen with the calcium ionophore A23187. TNF was co‐mitogenic with several phorbol esters known to activate PKC but was uneffective with inactive phorbol esters such as methyl‐phorbol 12‐myristate 13‐acetate. Furthermore, H‐7 a known inhibitor of PKC, inhibited the proliferative response of T cells induced by esters plus TNF. This effect took place at low doses of TNF and was also observed with purified T lymphocytes indicating that the effect of TNF was not dependent on accessory cells. This proliferative effect of TNF was inhibited by an anti‐interleukin 2 receptor (IL2R) antibody, MAR 108, which blocks IL 2 binding to its receptor. Although PKC activation induced CD25 (IL 2R) expression but very little IL 2 synthesis, TNF did not synergize by augmenting the synthesis of this lymphokine in peripheral blood lymphocytes stimulated with phorbol esters. By contrast, TNF strongly increased the membrane level of CD25 and to a lesser extent that of the activation antigen, 4F2, over the levels already induced by phorbol esters on T cells. More interestingly, TNF significantly increased the number of high‐affinity IL 2R on purified T cells in the presence of phorbol 12,13‐dibutyrate.Our results indicate that TNF is co‐mitogenic with those stimuli which strongly activate PKC and suggest that TNF may play a role on T cell activation increasing the number of effective IL 2/IL 2R interactions when these are limiting.
Influence of adenosine deaminase inhibition on the phosphoinositide turnover in the initial stages of human T cell activation
Authors: Buc Hélène A. , Moncion Arlette , Hamet Michèle , Houllier Anne‐Marie , Thuilier Laure , Perignon Jean‐Luis 
Published: March 2007

AbstractAn experimental model of adenosine deaminase deficiency was established on the human T cell line Jurkat by using 2'‐deoxycoformycin, a strong specific inhibitor of the enzyme. When deoxyadenosine was added to the inhibited cells, the nucleotide profile was modified reproducing that found in lymphocytes from adenosine deaminase‐deficient children. The metabolism of phosphoinositides, analyzed by either the release of [3H]inositol phosphates or the breakdown of 32P‐prelabeled phosphatidyl inositides, was compared in normal and modified cells where dATP was accumulated. No modification in 32P labeling of phosphoinositides was detectable within the 32P‐loading period. However, when the cells were stimulated by phytohemagglutinin or anti‐CD3 monoclonal antibody, the phosphoinositide hydrolysis was strongly reduced in the dATP‐containing lymphoblasts. This decrease was correlated with the intracellular dATP concentration.
Identification and immunogenic properties of an 80‐kDa surface antigen on a drug‐treated tumor variant: Relationship to MuLV gp70
Authors: Grohmann Ursula , Ullrich Stephen J. , Mage Michael G. , Appella Ettore , Fioretti Maria C. , Puccetti Paolo , Romani Luigina 
Published: March 2007

AbstractHighly immunogenic tumor variants are generated by in vitro or in vivo treatment of L5178Y murine lymphoma cells with triazene derivatives. Most of these variants express new transplantation antigens which are not present on the original L5178Y tumor cells. In this study, a polyclonal syngeneic antiserum raised to one such variant (L5178Y/DTIC) was employed in immunoprecipitation studies of cell surface and metabolically labeled L5178Y/DTIC cells. One‐ and two‐dimensional electrophoretic analyses of the immunoprecipitates detected a surface antigen of approximately 80 kDa. Additionally, a 45‐kDa component was detected in the lysate of [35S]methionine‐labeled cells. Anti‐xenotropic MuLV gp70 serum precipitated material whose electrophoretic pattern was similar to that of the 80‐kDa surface antigen. Sequential immunoprecipitation analysis revealed that the molecules reactive with the variant‐specific antiserum were removed by the anti‐xenotropic gp70 antibodies, whereas immunodepletion was only partial when the cell extract was first treated with the variant‐specific antibodies. After Western blotting, the 80‐ and 45‐kDa antigens precipitated by the variant‐specific antibodies were injected intrasplenically into recipient mice. Only the animals sensitized with the 80‐kDa antigen developed specific immunity to L5178Y/DTIC cells in that they displayed an increased frequency in CTL precursors (CTLp) to the variant cells. Sera from mice sensitized to the 80‐kDa protein specifically inhibited the development of a primary CTL response to L5178Y/DTIC cells.