bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyclic tetramolecular complexes of monoclonal antibodies: A new type of cross‐linking reagent
Authors: Lansdorp Peter M. , Aalberse Rob C. , Bos Rogier , Schutter Wilma G. , Van Bruggen Ernst F. J.
Published: February 2007

A simple and efficient procedure for the construction of bifunctional molecules is described and their use in a variety of applications documented. This procedure is based on our observation that mouse IgGl monoclonal antibodies, when mixed with equimolar amounts of a high‐affinity rat monoclonal antibody specific for mouse IgG1, yield uniform cyclic tetramolecular complexes each consisting of two mouse and two rat antibodies as shown by gel electrophoresis and electron microscopy. When solutions of two mouse antibodies (e.g. a and b) are mixed prior to the formation of complexes with the rat antibody, stable bispecific (a × b) complexes together with monospecific (a × a and b × b) complexes are obtained. Bispecific complexes prepared in this way were able to efficiently bind peroxidase to cell surface antigens, and to bind red blood cells to selected nucleated cell types present in heterogeneous populations. Tetrameric antibody complexes are more easily prepared than bispecific antibodies or bifunctional antibodies produced by transfection of myelomas with recombinant genes. They also have the advantage that the antigen‐binding properties of the bivalent monoclonal antibodies are not compromised. Tetrameric antibody complexes thus represent a powerful new type of cross‐linking reagent that may have a wide spectrum of applications in biology and medicine.
Role of IgE as a mast cell development co‐factor in the differentiation of murine gut‐associated mast cells in vitro
Authors: Kawanishi Hidenori
Published: February 2007

A role of IgE in the differentiation of gut‐associated mast cells (MC) was determined in vitro in the presence of a T cell product, interleukin 3 (IL3). The presence of both IL3 and IgE induced MC with higher precursor frequency than that of IL3 alone, by up to nearly 4 times, while IgE alone failed to develop the clonal growth of MC. IgE, but not the other isotype‐specific immunoglobulins, augmented the proliferation of IL3‐induced MC in the presence of IL3. Thus, IgE acts as a cofactor in the growth and/or differentiation of MC.
Mouse monoclonal antibodies induced by anti‐allotype antibody display internal images of the rabbit VHa1 allotype: Direct visualization by immunoelectron microscopy
Authors: Van Cleave Victor H. , Murti Kuruganti G. , Metzger Dennis W.
Published: February 2007

We have previously shown that injection of adult rabbits with anti‐immunoglobulin (Ig) antibody (Ab) induces the expression of genetically unexpected Ig markers, i.e., a1 allotypic determinants. We now show that these rabbit Ig markers can also be induced in mice by a similar treatment; in the latter case the a1 determinants are located in the antigen‐combining site and thus represent “internal images”. Two monoclonal antibodies (mAb) were developed from mice treated with anti‐allotype Ab. These mAb (a) were reactive with all homologous and heterologous anti‐a1 Ab but not normal Ig; (b) efficiently inhibited the binding of rabbit a1 Ig to anti‐a1 Ab; and (c) elicited the production of anti‐allotype Ab when injected into normal mice. To determine whether the al‐like determinants on these mAb were located in the antigen‐combining site, immunoelectron microscopy was utilized to directly visualize Ab complexes. Complexes composed of intact Ab and anti‐a1 Fab fragments yielded uniform binding patterns which were identical to those produced by anti‐idiotypic reactions. In each case, an identical tip‐to‐tip binding configuration was observed with a single Fab fragment attached at an approximate 180° angle to the V region terminus of each Ab arm. In contrast, rabbit a1 Ig bound as many as two anti‐a1 fragments per Ig arm; these fragments were attached laterally and at right angles to the intact molecule. These mAb thus provide the first direct evidence that Ab2β determinants are located in, or near, the antigen‐combining site.
Triggering of the lethal hit in human cytotoxic T lymphocytes: a functional role for a 103‐kDa T cell‐ specific activation antigen
Authors: Fleischer Bernhard , Schendel Dolores J. , Von Steldern Dierk
Published: February 2007

A monoclonal antibody (CB.1) is described that defines a new triggering signal for human cytotoxic T lymphocytes (CTL). The antibody precipitates a 103‐kDa surface antigen from activated normal human T cells. The antigen is undetectable or present in only low amounts on resting T lymphocytes but its expression increases strongly after activation and proliferation on T4+ and T8+ T lymphocytes. Binding of antibody CB.1 to CTL results in triggering of the lethal hit. This induction of cytotoxicity is dependent on cross‐linking of CTL and an Fc receptor‐bearing target cell with CB.1 and requires Ca2+ like antigen‐specific triggering. CB.1‐induced triggering can be specifically inhibited by binding of antibodies to the T8 or T4 molecules on T8+ or T4+ CTL.
Monoclonal antibodies against leucoagglutinin‐reactive human T lymphocyte surface components: Two antibodies which inhibit cell‐mediated cytotoxicity at a post‐binding stage
Authors: Vargas‐Cortes Mauricio , Hammarström Marie‐Louise , Hammarström Sten , Hellström Ulla , Perlmann Peter
Published: February 2007

Two out of 20 monoclonal antibodies (IgM,χ), mAb 3192 and mAb K3G, raised against leucoagglutinin‐reactive components on human T cells, effectively blocked lymphocyte‐mediated cytotoxicity in vitro. No antigenic polypeptide reactive with these antibodies has been identified thus far. However, they have previously been shown to react specifically with certain neutral glycolipids obtained from spleen. Both mAb inhibited the cytotoxicity of natural killer (NK) cells against K.562 cells, antibody‐dependent cellular cytotoxicity (ADCC) towards antibody‐coated bovine erythrocytes and cytotoxic T lymphocyte activity against allogeneic target cells. In both NK and ADCC, preincubation of the lymphocytes with different antibody concentrations resulted in a dose‐dependent reduction of cytotoxicity. In contrast, preincubation of the target cells had no effect indicating that the mAb inhibited cytotoxicity at the effector cell level. When studied at the single‐cell level, the mAb did not alter the number of lymphocytes forming conjugates with K562 but significantly reduced the frequency of conjugates containing dead target cells. Addition of the mAb to preformed conjugates resulted in a dose‐dependent reduction in the proportion of conjugates containing dead target cells. Furthermore, mAb 3192 did not reduce the number of lymphocytes forming rosettes with bovine erythrocytes, indicating that inhibition of ADCC was not due to blocking of the effector cell‐target cell interaction mediated by the Fc receptor of the effector cells. Taken together, these results suggest that the mAb inhibited cytotoxicity by interfering with a post‐binding step common for the different cytotoxicity systems.
Thymic nurse cells: a school for alloreactive and autoreactive cortical thymocytes?
Authors: Wick Georg , Oberhuber Georg
Published: February 2007

The possibilities for functional analysis of thymic nurse cells (TNC) have so far been hampered by the low yield of these cells by means of gradient centrifugation and their fragility preventing purification by a fluorescence‐activated cell sorter. Furthermore, they are extremely unstable in cell culture. Here we present functional data obtained by the analysis of single TNC in an avian system: the chicken with its extramaternal embryonic development prompted us to use the chorioallantoic membrane (CAM) pock formation assay to investigate the possible graft‐vs.‐host reactivity (GVHR) of TNC lymphocytes (TNC‐L). The CAM assay proved to be an optimal and unique “cell culture” system for the investigation of the functional characteristics of TNC. Our data show that TNC‐L, unexpectedly, are able to exert a GVHR on allogeneic CAM with the very high efficiency of 1/13 as compared to thymocytes of the same donors showing a GVHR efficiency of 1/350. TNC‐L are even able to induce GVH‐like reactions in syngeneic combinations, while thymocytes and peripheral blood lymphocytes from the same donors always remain negative.
myo‐Inositol reverses Li+‐induced inhibition of phosphoinositide turnover and ornithine decarboxylase induction during early lymphocyte activation
Authors: Mustelin Tomas , Pösö Hannu , Iivanainen Antti , Andersson Leif C.
Published: February 2007

One of the earliest detectable responses by T lymphocytes in vitro to various mitogenic ligands is the rapid induction of ornithine decarboxylase (ODC) activity (Scott et al., Eur. J. Immunol. 1985. 15: 783). This early activation is measurable within minutes after the addition of the mitogen. The T cell mitogen concanavalin A also induces rapid breakdown of phosphoinositides in T lymphocytes. The inositol phosphates formed are recycled and used in synthesis of new phosphoinositides. Li+interrupts this cycle by inhibiting the enzyme inositol‐1‐phosphatase, which produces the inositol needed for phosphoinositide synthesis.

Here we report that when human blood lymphocytes are kept in an inositol‐deficient medium for 30 min in the presence of 1 mM Li+, the cells become unable to respond to mitogens by inositide breakdown and rapid induction of ODC activity. Addition of 1 mM myo‐inositol restores the inducibility of these responses within a few minutes. These findings represent a novel aspect of the activation of resting lymphocytes and implies a new role for the inositol turnover during signal transduction.
Co‐expression of different types of Fc receptors on murine peritoneal macrophages
Authors: Větvička Václav , Fornů Lubor , Kincade Paul W. , Kopeček Jindrich
Published: February 2007

Simultaneous expression of particular immunoglobulin Fc receptors (FcR) was studied on the plasma membranes of murine peritoneal macrophages. This was facilitated by the use of sheep red blood cells (SRBC) and/or synthetic microspheres coated with monoclonal antibodies of different isotypes. It was concluded that a majority of macrophages bear more than one type of FcR; macrophages bearing at least three types of FcR were present in the peritoneal cavity; macrophages bearing FcμR did not bind IgE, IgA or IgG; all macrophages bearing FcαR also expressed Fcγ2bR, Fcγ3R, and FcεR; all macrophages bearing FcεR also expressed Fcγ2bR and FcαR. Except for FcαR, essentially equivalent numbers of FcR‐bearing macrophages were detected when antibody‐coated SRBC or polymeric microspheres were used. Simultaneous applications of these reagents permitted the most detailed and direct investigations yet performed of multiple FcR expression on individual cells.
Fine specificity of antibodies produced in rhesus monkeys following in vivo treatment with anti‐T cell murine monoclonal antibodies
Authors: Villemain Françcoise , Jonker Margreet , Bach Jean‐François , Chatenoud Lucienne
Published: February 2007

The immune response of 23 rhesus monkeys against different murine monoclonal antibodies (mAb) administered in vivo as immunosuppressive agents has been analyzed. Seven mAb specific for either helper‐inducer (CD4 molecules) or cytotoxic/suppressor (CD8 molecules) T cells, that cross‐react with monkey lymphocytes, were administered i.v. for 10 consecutive days in rhesus monkeys. Nineteen of the animals were recipients of a skin or renal allotransplant. Nineteen out of the 23 monkeys developed a significant immune response against the injected monoclonal. This response was restricted in its specificity since unrelated murine monoclonals were not recognized by the monkeys' anti‐monoclonal immunoglobulins. Fine analysis of the monkeys' sera revealed that the antibodies produced against the xenogeneic proteins selectively exhibited two major specificities i.e., anti‐isotypic and anti‐idiotypic. On practical basis, these results suggest that an animal already immunized against a given mAb should still be sensitive to the therapeutic effect of another monoclonal sharing the same specificity but different idiotype.
Suppression of specific IgM, IgA and IgG responses in mice treated with anti‐6 from birth
Authors: Wathen Patricia M. , Manning Dean D.
Published: February 2007

In contrast to previous studies, we report that heterologous anti‐δ antibodies can act as a powerful multi‐class humoral immunosuppressant. Primary direct plaque‐forming cell (IgM) responses of BALB/c mice injected from birth with a rabbit anti‐δ antiserum were reduced to 3% of control levels against a T‐dependent antigen (sheep red blood cells), and to 2% against a T‐independent antigen (dextran); IgA responses against 2 intraduodenal injections of cholera toxin were reduced to 7% of control levels. Other secondary immune responses of anti‐δ‐suppressed mice were suppressed to a lesser degree. IgM plaque responses generated by 2 injections of sheep red cells, for example, were reduced to 50% of control levels, with reduction of the corresponding IgG response to 42%.

The multi‐class suppression observed indicates a clonal differentiation pathway in which the IgD+ cell develops into IgM‐, IgA‐ and IgG‐secreting cells. In light of reports that the IgD+ cell is antigen sensitive, our demonstration that IgD is capable of delivering the same sort of immunosuppressive signal in response to anti‐heavy chain antibodies that IgM delivers also suggests, though it does not establish, an antigen‐receptor role for IgD.
Evidence for distinct epitopes on human IgG with T cell proliferative and suppressor function
Authors: Baxevanis Constantin N. , Ioannides Constantin‐Demosthenes G. , Reclos George J. , Papamichail Michael
Published: February 2007

The Fc or pFc' fragments of the human IgG were demonstrated to exert different effects on murine T lymphocyte subsets. Thus, murine lymph node (LN) T cells were specifically induced to proliferate in vitro to pFc' after priming in vivo. This proliferation could be inhibited, either by depleting the responding LN population of macrophages, or by monoclonal antibodies specific for responder haplotype Ia antigenic determinants. Priming in vivo and subsequent restimulation in vitro with Fc resulted in the activation of a suppressor T cell subpopulation which, in an antigen‐specific manner, could highly suppress proliferative responses. T cell subset isolation showed that the pFc'‐specific proliferation was performed by Lyt‐l+2− cells whereas the suppressor Fc‐specific cells were of Lyt‐l−2+ phenotype. Our data demonstrate that distinct epitopes on the human γ chain induce either Ir gene‐restricted T cell proliferation (pFc' fragment) or T cell suppressor function (Fc fragment).
Ontogeny of priming of cytotoxic T cells to minor alloantigens: the development of direct priming precedes that of cross‐priming
Authors: Rafii‐Tabar Elahe , Czitrom Andrei A.
Published: February 2007

Cytotoxic T lymphocytes of heterozygous adult mice primed in vivo with minor alloantigens on cells of one parental H‐2 genotype can be boosted in vitro to respond to minor alloantigens on cells of both the immunizing parental H‐2 genotype (direct priming) and of the H‐2 genotype of the other parent (cross‐priming). We studied the ontogeny of this phenomenon and show that during early postnatal life the development of direct priming precedes that of cross‐priming. The delayed maturation of cross‐primed responses parallels the known development time sequence of functional antigen‐presenting cells and provides evidence for the explanation of cross‐priming in terms of antigen processing.
Composition of the lymphoid cell populations from omental milky spots during the immune response in C57BL/Ka mice
Authors: Paper Short , Dux Kazimir , Rouse Robert V. , Kyewski Bruno
Published: February 2007

The lymphoid cell composition of milky spots was analyzed in unprimed mice before and after i.p. immunization with sheep red blood cells. Milky spots contained surface immunoglobulin‐positive B lymphocytes, and T cells of the helper and cytotoxic phenotype. After secondary antigen challenge (a) the number of lymphocytes increased up to 40‐fold, (b) B and T cells were found to segregate into distinct areas in situ, and (c) lymphocytes were found to associate with I‐A‐negative stromal cells in vivo. These findings qualify milky spots as a peripheral lymphoid organ exhibiting a remarkable change in number and composition of lymphocytes in response to a local antigen stimulus.
T cell help in human antigen‐specific antibody responses can be replaced by interleukin 2
Authors: Callard Robin E. , Smith Susan H. , Shields John G. , Levinsky Roland J.
Published: February 2007

Recombinant IL2, and immunosorbent/high performance liquid chromatography‐purified interleukin 2 (IL2) obtained from the human T cell leukemic line Jurkat, but not interferon‐α or ‐γ, were able to substitute for T cells in specific antibody responses to influenza virus by T cell‐depleted (E−) human peripheral blood mononuclear cells, and resulted in antibody formation equivalent to that obtained in the presence of T cells. The antibody response was shown to be antigen specific by using two non‐cross‐reacting strains of influenza virus (A/X31 and B/HK). IL2 in this assay therefore functions as a T cell‐replacing factor. Less than 1 % of T (UCHT1+) cells were present in the E− preparations, and this number did not increase during the 7‐day culture with antigen and IL2. Because the frequency of T helper cells for X31 is known to be less than 5 ± 10−5, this low number of contaminating cells excluded indirect action of IL2 through antigen‐specific T helper cells. Three to four times less IL2 was required for antibody production by E− cells than was needed for optimal proliferation by an IL2‐ dependent T cell line. Moreover, the concentration of anti‐Tac required for 50% inhibition of the IL 2‐induced antibody response was 50 times less than required for 50% inhibition of IL2‐dependent proliferation by the T cell line. But when T cells were added back to the E− cells, the anti‐Tac inhibition curve shifted back to that obtained with the T cell line. In cell labeling experiments, Leu11+ cells but not HNK1+ cells were increased in E− cells cultured with antigen and IL2. This increase in Leu 11+ cells was abolished by prior passage of the E− cells through Sephadex G‐10 columns without affecting the IL2‐induced antibody response. From these experiments we conclude that IL2 can replace T cells in specific antibody responses, and that the IL 2 effect is not mediated indirectly through T cells or large granular lymphocytes.
Interaction of periodate‐oxidized target cells and cytolytic T lymphocytes: a model system of “polyclonal MHC recognition”
Authors: Keren Zvi , Berke Gideon
Published: February 2007

In oxidation‐dependent cytotoxicity (ODCC), cytolytic T lymphocytes (CTL) non‐specifically recognize, bind to and lyse oxidized target cells (O‐TC) but the precise mechanism whereby CTL react with O‐TC is far from clear (Berke, G., Immunol. Rev. 1983. 72: 5). Here we present evidence that CTL/O‐TC interactions are blocked by aldehyde‐reactive reagents such as hydroxylamine, adipic acid dihydrazide and thiocarbohydrazide and that preformed CTL/O‐TC conjugates dissociate upon reduction with NaBH4, suggesting that active aldehyde groups of O‐TC rather than intercellular Schiff bases are involved in the recognition and lysis of O‐TC by CTL in ODCC. The aldehydes are bound to trypsin‐sensitive, non‐H‐2 glycoproteins that appear to be different and unique in the three different target cell lines so far examined (EL4, L1210, R1.1). In view of these and previous findings we would like to suggest that in ODCC, active aldehydes react with adjacent major histocompatibility complex and perhaps other cell‐surface molecules to create a multitude of modified conformations, responsible for the “polyclonal” (nonspecific) MHC recognition and lysis of O‐TC by CTL, as well as for an altered pattern of H‐2 antibody binding to O‐TC.
Anti‐CD2 (sheep red blood cell receptor) monoclonal antibodies and T cell activation I. Pairs of anti‐T11.1 and T11.2 (CD2 subgroups) are strongly mitogenic for T cells in presence of 12‐O‐tetradecanoylphorbol 13‐acetate
Authors: Olive Daniel , Ragueneau Marguerite , Cerdan Chantal , Dubreuil Patrice , Lopez Marc , Mawas Claude
Published: February 2007

A large collection of monoclonal antibodies (mAb) directed against sheep red blood cell (SRBC) receptor (cluster of differentiation 2 : CD2) were classified according to three criteria: (a) their inhibitory effect on T cell‐SRBC rosette formation; (b) the epitopic cluster recognized on the CD2 molecule; (c) their reactivity with resting or activated T cells. All mAb were then tested in a two by two checkerboard fashion for possible T cell mitogenicity, in presence or absence of a submitogenic dose of 12‐O‐tetra‐decanoylphorbol 13‐acetate (TPA), an agent known to be comitogenic for T cells, presumably in delivering a second signal, usually accessory cell dependent. The combined data demonstrate that in the absence of TPA only few pairs of mAb directed at distinct epitopes of the CD2 molecule were mitogenic for T cells (in approximately 30% of the population tested), and in the presence of a submitogenic dose of TPA the majority of T11.1 anti‐CD2‐mAb (9 out of 11) were strongly mitogenic for T cells of all individuals tested when paired with T11.2 anti‐CD2 mAb. The two anti‐T11.1 mAb, noncomplementary to anti‐T11.2 mAb, were, however, strongly mitogenic when added to mAb of the T11.3 subgroup, represented by 1‐Mono‐2A6.

Taken together, these data strongly suggest that the main characteristic of T cell mitogenesis triggered by anti‐CD2 mAb is the requirement for a signal delivered simultaneously to two different epitopes of the CD2 molecule, whether these epitopes are T11.1, T11.2 or T11.3.
Detection of rearranged T cell receptor β‐chain gene and induction of cytolytic function in interleukin 2‐ responsive day 14–15 murine fetal thymocytes
Authors: Hardt Conny , Fleischer Sabine , Steinmetz Michael , Wagner Hermann
Published: February 2007

A subpopulation of interleukin 2 (IL 2) receptor‐positive day 14–15 murine fetal thymocytes can be induced by recombinant IL 2 to proliferate over prolonged time periods in dissociated cell cultures. The proliferating day 14–15 fetal thymocytes exhibit no cytolytic effector function, nor do they rearrange T cell receptor β chain genes. This contrasts with thymic organ cultures in which day 14–15 thymocytes do rearrange β chain genes and give rise to immunocompetent cells. However, such events can also take place in dissociated cell cultures, provided the IL 2‐responsive thymocytes are cultured on syngeneic feeder cells in the presence of IL 2 and the mitogen concanavalin A. Under such conditions rearrangement of the β chain gene complex becomes detectable and cytolytic effector cells are generated. The frequency of inducible cytolytic precursor cells in day 14–15 thymocytes is 1/7000. These data either imply that immunocompetent cells are already present in the day 14–15 fetal thymus, or differentiation from precursors to immunocompetent cells must occur in dissociated cell cultures.
Interleukin 2 is a proliferative signal for B cells from autoimmune mice
Authors: Lehmann Kathrin R. , Kotzin Brian L. , Portanova Joseph P. , Santoro Thomas J.
Published: February 2007

T cells from murine lupus strains manifest complex defects in interleukin 2 (IL 2) production and receptor expression. The capacity of B cells from such mice to utilize IL2 as a growth factor has not been previously reported and is examined herein. Anti‐Thy‐1.2 plus complement‐treated spleen cells from 6–8‐week‐old autoimmune MRL‐ Ipr/lprmice and from age and sex‐matched immunologically normal CBA/J mice were cultured with lipopolysaccharide (LPS) for 36 h and analyzed for the expression of IL 2 receptors using the monoclonal antibody 7D4. The percentage of B cells expressing IL2 receptors was comparable in MRL‐lpr/lpr and CBA/J mice. In contrast to those from CBA/J, BALB/c and (BALB/c × NZW)F1 mice, LPS‐stimulated B cells from MRL‐lpr/lpr and from (NZB × NZW)F1 mice were capable of proliferating in response to IL 2. Fractionation of MKL‐lprl/lprB cells using Percoll gradient density separation demonstrated that the IL2‐responsive population consisted predominantly of large cells. In addition, unfractionated B cells from MRL‐lpr/lpr mice were found to be substantially more responsive to IL2 than those from CBA/J and BALB/c mice following activation with anti‐immunoglobulin plus LPS. The hyper‐responsiveness to IL 2 may be a consequence of the state of activation of autoimmune B cells and is of potential importance in the pathogenesis of systemic lupus erythematosus.
A comparison of eosinophil‐activating factor (EAF) with other monokines and lymphokines
Authors: Thorne Kareen J. I. , Richardson Brian A. , Taverne Janice , James Williamson D. , Vadas Mathew A. , Butterworth Anthony E.
Published: February 2007

Monocytes from moderately eosinophilic individuals secrete material that enhances the cytotoxic activity of eosinophils against antibody‐coated schistosomula of Schistosoma mansoni. This material is not a single substance, but can be fractionated into several active components of different size and different charge. Gel filtration of mononuclear cell supematants separated the eosinophil‐activating activity into a major component of molecular mass of 40 kDa and a minor component of molecular mass of < 10 kDa. The major component exhibited further heterogeneity on fractionation by high performance liquid chromatography. The bulk of the eosinophil‐activating activity could be separated from both colony‐stimulating factor (CSF)α activity and from tumor necrosis factor (TNF) activity. However, human recombinant CSFα (GM‐CSF), human recombinant TNF and rabbit tumor necrosis serum all had eosinophil‐activating activity when tested against schistosomula. Eosinophils were not activated by interleukin 1, interleukin 2, interferon‐α, lipopolysaccharide or phorbol myristate acetate.
T cell clones which share T cell receptor epitopes differ in phenotype, function and specificity
Authors: Yssel Hans , Blanchard Dominique , Boylston Art , De Vries Jan E. , Spits Hergen
Published: February 2007

Recently, we described a monoclonal antibody (3D6) that reacts with the T cell receptor (Ti) of the T leukemic cell line HPB‐ALL and that cross‐reacts with 2–10% of the T cells of normal healthy individuals. In this study we report the establishment of T cell clones that are 3D6+ but that differ in function and phenotype. These clones were established according to two different protocols: (a) T cells of donor HY (10% 3D6+) were stimulated with the Epstein‐Barr virus‐transformed cell line JY. The proliferating 3D6+ T cells were enriched using a rosetting technique and cloned, (b) T cells of donor HY were stimulated with the 3D6 antibody and subsequently expanded in recombinant interleukin 2‐containing medium. This yielded 70% 3D6+ T cells which after activation with either Daudi cells or with TT in the presence of autologous non‐T cells, followed by cloning, resulted in antigen‐specific 3D6+ T cell clones. The 3D6+ T cell clones were also tested on their reactivity with 4 other monoclonal antibodies (1C1, 1C2, 2D4, 65) specific for the Ti of HPB‐ALL. The antibodies 1C1 and 1C2 reacted with all 3D6+ T cell clones and recognize probably the same epitope as 3D6. The antibodies 2D4 and 65 reacted with two mutually exclusive subsets of T cell clones. All the anti‐Ti antibodies reacted with functional epitopes, since they were able to block the function of the T cell clones. The specificity of the clones was investigated by blocking studies using monoclonal antibodies specific for different major histocompatibility complex antigens. No correlation was found between the expression of the different Ti epitopes and the specificity, the CD4/CD8 phenotype or function of the clones.
A lymphoid cell surface glycoprotein involved in endothelial cell recognition and lymphocyte homing in man
Authors: Jalkanen Sirpa T. , Bargatze Robert F. , Herron Lynne R. , Butcher Eugene C.
Published: February 2007

We describe a 90‐kDa lymphocyte surface glycoprotein, recognized by the monoclonal antibody Hermes‐1, that is involved in endothelial cell recognition and lymphocyte trafficking in man. This molecule (a) is selectively expressed on normal or transformed lymphoid cells that are able to recognize and bind to high endothelial venules (HEV, specialized vessels that mediate lymphocyte exit from the blood into lymphoid organs); (b) appears to be linked to HEV recognition function since, in fluorescence‐ activated cell sorting of variants of a cloned cell line, HEV binding ability co‐selects with the Hermes‐1 antigen; (c) bears the predominant cell surface epitopes recognized by heterologous anti‐human lymphocyte antibodies able to interfere with lymphocyte binding to HEV; and (d) is structurally similar to a previously described mouse lymphocyte surface receptor for HEV. These findings demonstrate that the molecule defined by Hermes‐1 either functions as a specific lymphocyte surface receptor for HEV, or is both precisely coregulated and physically and/or functionally associated with such receptors. The expression of this putative receptor for HEV on normal human lymphocyte populations parallels, and thus presumably helps determine, their migratory status in vivo. Hermes‐1 should be a powerful tool for analyzing the role of endothelial cell recognition in the traffic of normal and neoplastic human lymphocytes.
Control of cell proliferation within the human thymus. A very limited thymocyte subpopulation generates a suppressive activity
Authors: Gelin Catherine , Boumsell Laurence , Bernard Alain
Published: February 2007

It is shown here that a minor subpopulation of the human thymus, representing 2–3% of the whole thymocyte population, can suppress proliferation of syngeneic or allogeneic thymocytes to various stimuli. In contrast, this suppressor cell population has no influence on the proliferative response of peripheral blood lymphocytes. This subpopulation was defined by its cell surface phenotype as CD3+, CD1−, 4−, 8− cells. Its suppressive activity is generated after concanavalin A (Con A) stimulation, but not after stimulation with phytohemagglutinin. In addition, the suppressive activity is not modified by extensive washes of Con A‐stimulated cells with 1‐O‐methyl‐α‐D‐ glucopyranoside, a specific sugar for Con A. This suppressor cell population does not exert any detectable cytotoxic activity, nor does it act by consuming available interleukin 2 (IL2). Rather, it prevents IL2 receptor expression on thymic target cells. Since Con A might activate T cells by binding to molecules physiologicaly involved in T cell activation, particularly the CD3‐T cell receptor complex, these data could be relevant to the regulation of normal thymic differentiation.
Modulation of c‐fos and c‐myc mRNA levels in normal human lymphocytes by calcium ionophore A23187 and phorbol ester
Authors: David Grausz J. , Fradelizi Didier , Dautry François , Monier Roger , Lehn Pierre
Published: February 2007

A transient expression of the proto‐oncogenes c‐fos and c‐myc is rapidly induced by growth factors or mitogens in different cell types including lectin‐stimulated lymphocytes. To elucidate the early events of lymphocyte activation, we determined (by Northern blot analysis) the steady‐state levels of c‐fos and c‐myc mRNA in normal human peripheral blood lymphocytes (PBL) stimulated with the Ca2+ ionophore A23187 and/or 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), whose biological activities are well defined. We report that ionophore A23187 (0.5 mUM) or, to a significantly lesser extent, TPA (0.5 ng/ml), neither of which is mitogenic alone at these concentrations, nevertheless can induce a transient accumulation of the protooncogene transcripts. These results indicate that a significant accumulation of c‐fos and c‐myc mRNA can occur without subsequent lymphocyte proliferation. The combination of these two mitogens increases the induced levels of both types of c‐onc mRNAs. The level of mRNA accumulation correlates with the degree of proliferation induced by mitogenic combinations of ionophore A23187 and TPA, as measured by [3H]thymidine incorporation. Thus, these compounds act synergistically both with respect to c‐fos and c‐myc mRNA accumulation and to mitogenicity in human PBL.

We also studied the level of c‐fos transcripts following stimulation of the T lymphocyte T3/Ti receptor complex, using monoclonal anti‐T3 antibodies. We observed that mitogenic doses of anti‐T3 also induce an accumulation of c‐fos mRNA, whose induction also is synergized by TPA. These results suggest that transient accumulation of c‐fos‐, as well as c‐myc, mRNA is a normal event of the immune response. They confirm that Ca2+ ionophore combined with TPA can mimic some molecular features of the early steps of normal human PBL activation.
Role of the major histocompatibility complex in targeting effector T cells into a site of virus infection
Authors: Doherty Peter C. , Allan Jane E.
Published: February 2007

Bone marrow radiation chimeras have been used as virus‐infected, cyclophosphamide‐suppressed recipients to analyze the major histocompatibility complex (MHC) restriction constraints on the adoptive transfer of lymphocytic choriomeningitis by immune T cells. The basic protocol employed [(A × B)F1→(A × C)F1] chimeras, where A, B, C are different MHC haplotypes, and the establishment of appropriate chimerism was measured by the capacity of, for instance, the transferred A, T cells to generate MHC‐restricted, virus‐specific cytotoxic T lymphocytes (CTL) in the spleen of the [(A × B)F1 →(B × C)F1] recipients. The experiments show quite clearly that maximal inflammatory process is only induced when donor bone marrow, irradiated recipient and transferred T cells share at least one MHC haplotype. Compatibility of the T cells and the radiation‐resistant phenotype alone in, for instance, transfer of C immune lymphocytes into [(A × B)F1→ (B × C)F1] recipients produced little inflammation if the chimeras had been established for at least 10 weeks. These results are compatible with a model which proposes that the transferred T cells first replicate in MHC‐compatible lymphoid tissue and are then targeted onto the appropriate MHC plus virus expressed on cells in the blood‐cerebrospinal fluid (CSF) barrier. An alternative postulate, that all that is required for the development of inflammatory process is MHC‐restricted T cell replication in lymphoid tissue, with subsequent nonspecific localization to the central nervous system (CNS), was explored by transferring B, immune T cells into [(A × B)F1→ A] recipients. The finding was that H‐2b effectors did not cause any meningitis in [H‐2k×bFl→ H‐2k] recipients, though potent H‐2b‐restricted CTL were generated in the spleens of comparable chimeras. However, in the H‐2k immune → [H‐2k×bF1 → H‐2b] transfer there was evidence of moderate inflammation that was about 9 times less severe than that caused by the H‐2b effectors in comparable recipients. This indicates that, for maximal inflammatory process to occur, the T cells must encounter MHC‐compatible, virus‐infected cells in the CNS, with the effect being absolute in one strain combination and partial in another. Possible mechanisms underlying this divergence are discussed.
Mice naturally tolerant to C5 have T cells that suppress the response to this antigen
Authors: Cairns Lloyd , Rosen Fred S. , Borel Yves
Published: February 2007

We examined whether C5‐sufficient mice which are naturally tolerant to this antigen have suppressor T cells to C5 humoral immune response. Two congenic strains of mice B10.D2 (NSN) and B10.D2 (OSN) differing only in the presence or absence of C5 were used. Irradiated (760 rds) sufficient hosts were reconstituted with a nonadherent spleen cell suspension from either sufficient or deficient mice or a mixture of both. Hemolytic C5 levels were assayed. Sufficient spleen cells appeared to prevent the drop of C5 level caused by anti‐C5 antibody made by deficient spleen cells. Spleen cell suspensions from sufficient mice primed with deficient spleen cells exhibited better anti‐C5 activity than normal sufficient spleen cell suspensions. This anti‐C5 activity is abrogated by treatment of the NSN spleen cell suspensions obtained from NSN primed with OSN spleen cells with anti‐Thy‐1.2 antiserum and complement. Suppression of the humoral response to C5 failed to affect the anti‐sheep red blood cell immune response. Suppressor T cells are resistant to low‐dose irradiation, cortisone treatment and adult thymectomy. In contrast, they are sensitive to high doses of irradiation and both high and low doses of cyclophosphamide treatment. Thus, C5 sufficient mice, in contrast to C5‐deficient mice, appear to have antigen‐specific suppressor T cells which downregulate the humoral immune response to C5.

In addition, we examined the relationship of these suppressor T cells to the state of tolerance in helper T cells of C5‐sufficient mice. This was done in irradiated deficient mice which were repopulated with spleen cell suspensions selectively depleted of either Lyt‐l+ or Lyt‐2+ T cell subsets. These chimeras were challenged with murine C5 and both the primary and secondary immune response was measured by inhibition of the C5 hemolytic activity. It was found that only spleen cell suspensions of the deficient mice selectively depleted from the Lyt‐2+ subset of T cells responded to the antigen both in the primary and secondary response. In contrast, either subset of T cells from the sufficient mice failed to respond. Thus, it appears that in sufficient mice helper T cells to C5 are intrinsically tolerant or physically and/or functionally deleted. In conclusion, the data suggest that both T cell compartments are unresponsive and play a role in the mechanism of tolerance to a physiologic antigen.
T cell receptor expression and receptor‐mediated induction of clonal growth in the developing mouse thymus. High surface β‐chain density is a requirement for functional maturity
Authors: Nicholas Crispe I. , Husmann Linda A. , Bevan Michael J.
Published: February 2007

The ontogeny of T cell antigen receptor expression and function in the mouse thymus has been studied using a monoclonal antibody, F23.1, which recognizes a determinant on the β chain of the receptor, and stains 25% of mature T cells and around 7‐15% of adult thymocytes from most mouse strains. The same monoclonal antibody selectively activates Lyt‐2+ peripheral T cells. Receptors are detectable by staining and fluorescence‐activated cell sorter analysis from fetal day 17, and thereafter the overall frequency increases steadily towards adult levels. However, late fetal thymocytes express all of their antigen receptor β chain at a very low level, visible by staining as a “shoulder” on the peak of negative cells. Thymocytes with high‐density surface β chain, visible by staining as a distinct peak, appear only after birth and are a prominent feature at neonatal day 4. In the late fetus, expression of β chain can be detected on thymocytes with the “mature” L3T4−, Lyt‐2+ phenotype. Despite this, F23.1 responsive precursors are not found in the fetal thymus, and appear in two waves, the first during day 1 of postnatal life and the second between days 3 and 4. These data suggest that high‐density surface expression of T cell receptor β chain occurs in parallel with functional maturation.
T90/44 (9.3 antigen). A cell surface molecule with a function in human T cell activation
Authors: Lesslauer Werner , Koning Frits , Ottenhoff Tom , Giphart Marius , Goulmy Els , Van Rood Jon J.
Published: February 2007

T90/44 is a cell surface antigen which is present on human T cells of the helper and cytotoxic subsets and which binds the 9.3 monoclonal antibody (9.3 mAb). It is expressed in the form of 90‐kDa disulfide‐bonded dimers of a 44‐kDa polypeptide and of free 44‐kDa subunits. The function of T90/44 was investigated in a series of T cell function assays. 9.3 mAb was found to inhibit the activation of class II‐restricted cloned T helper cells derived from leprosy patients and reactive with M. leprae antigens. The inhibition was first found at 1–10 ng/ml 9.3 mAb and regularly increased with the antibody concentration. The extent of the inhibition varied among different T cell clones in proportion to the respective different levels of T90/44 expression at their cell surface. The proliferative responses of peripheral blood lymphocytes (PBL) to purified protein derivative of M. tuberculosis (PPD) and tetanus toxoid were enhanced by the 9.3 mAb resulting in up to 20–30‐fold increase of [3H]‐thymidine incorporation. After phytohemagglutinin‐induced activation of PBL, the number of T90/44 molecules per cell expressed at the cell surface rose from day 0 to day 7 by a factor of about 10. High concentrations of 9.3 mAb (5–10 μ/ml) at low cell densities and in the presence of monocytes in culture media supplemented by fetal calf serum were directly mitogenic for resting lymphocytes. The cytolytic effector functions of class I‐restricted cytotoxic T lymphocytes (CTL) were not modulated by 9.3 mAb. The mixed lymphocyte reactions of three class I‐restricted CTL to their specific target cells were found not to be significantly influenced bv 9.3 mAb. In conclusion it is proposed that an antigen‐independent T cell activation pathway can be entered at T90/44.
Purification of an antibody‐like protein from the sea star Asterias rubens (L.)
Authors: Delmotte Francis , Brillouet Claude , Leclerc Michel , Luquet Gilles , Kader Jean‐Claude
Published: February 2007

Cells from sea star (Asterias rubens) axial organs stimulated with trinitrophenyl (TNP) or fluoresceinyl‐haptened polyacrylamide beads and subsequently stimulated in vitro with the same antigen produced and released a specific antibody‐like protein which induced lysis of haptened sheep erythrocytes in the presence of serum complement. The anti‐TNP antibody‐like protein isolated by ammonium sulfate precipitation, gel filtration and affinity chromatography exhibited a single precipiting peak after crossed immunoelectrophoresis against rabbit antiserum to partially purified culture supernatant. The anti‐TNP antibody‐like protein gave a specific affinity precipitate in crossed affino‐electrophoresis using a p‐nitrobenzoyl‐substituted gel. The analysis by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis under both reducing and nonreducing conditions evidenced a unique 30‐kDa polypeptide chain. According to gel filtration experiments, the molecular weight of the major component isolated by affinity chromatography was about four times higher. Therefore, the antibody‐like molecule could be a tetrameric protein devoid of any disulfide bond.
Autoantibodies against gp140, the Epstein‐Barr virus and C3d receptor in sera from rheumatoid arthritis patients
Authors: Barel Monique , Kahan Alice , Charriaut‐Marlangue Christiane , Kahan André , Frade Raymond
Published: February 2007

Gp140 is the Epstein‐Barr virus receptor and the C3d receptor (EBVR/C3dR) of human B lymphocytes. Recently, we have shown that cross‐linking of EBVR/C3dR on cell surface by polyclonal anti‐gp140 induced B cell activation, in presence of T cell factors.

Immunoregulatory abnormalities of EBV‐induced B cell activation have been demonstrated in rheumatoid arthritis (RA) patients. These data prompted us to analyze the putative presence of anti‐EBVR/C3dR autoantibodies in human sera. The IgG fractions from eleven RA and 10 normal sera were tested for their ability to: (a) bind to Raji cell surface; (b) inhibit the binding to cell surface of 3 anti‐EBVR/C3dR monoclonal antibodies (mAb), which recognized different epitopes on gp140; (c) inhibit the binding of particle‐bound C3d and (d) react with 1% Nonidet‐P40‐solubilized gp140 from Raji cell membranes, in immunoblotting assays. Three RA sera carry anti‐ EBVR/C3dR autoantibodies which react with gp140 expressed on Raji cell surface or its solubilized form. The purification of monomeric IgG fraction of selected RA sera ruled out involvement of immune complexes carrying C3 molecules, which could interfere in these assays. One of these 3 RA sera was able to inhibit the binding to cell surface of anti‐EBVR/C3dR mAb and particle‐bound C3d. However, the 2 other RA sera, found positive by immunoblotting, did not inhibit particle‐bound C3d and presented differences in their inhibitory effect on anti‐EBVR/C3dR mAb binding to Raji cell surface. These data allow us to demonstrate differences which exist in the properties of anti‐EBVR/C3dR autoantibodies. These autoantibodies were not detected in all the normal and other RA sera. Anti‐EBVR/C3dR autoantibodies could play a role “in vivo” in B lymphocyte activation of RA patients.
Evidence for a regulatory role of the T8 (CD8) antigen in antigen‐specific and anti‐T3‐(CD3)‐induced lytic activity of allospecific cytotoxic T lymphocyte clones
Authors: Van Seventer Gijs A. , Van Lier René A. W. , Spits Hergen , Ivanyi Pavol , Melief Cornells J. M.
Published: February 2007

The functional role of the T8 antigen of human T cells was studied by inhibition with anti‐T8 monoclonal antibodies (mAb) of the cytotoxic action of T8+ cytotoxic T lymphocyte clones (CTL). All clones were allospecific and directed against HLA‐B7. The ability of seven different anti‐T8 mAb to inhibit the cytotoxicity of these alloreactive CTL clones corresponded with their avidity for a particular target cell. The lysis of cross‐reactive antigen‐bearing target cells was more readily blocked by anti‐T8 mAb than lysis of the specific B7 target cell against which a clone was raised. The seven anti‐T8 mAb showed a spectrum of CTL blocking ability ranging from strong blocking with all five CTL clones tested to weak inhibition of only two out of five clones. mAb inhibition of CTL reactivity and cold target inhibition studies with one of the five CTL clones indicate a post‐binding role of the T8 molecule. Functional epitope mapping based on CTL blocking with the anti‐T8 mAb resulted in the definition of one nonfunctional epitope on the T8 molecule which is only expressed on mature T lymphocytes and a cluster of closely related functional epitopes expressed on both thymocytes and mature T lymphocytes.

Not only allospecific cytotoxicity, but also nonspecific cytotoxicity induced by anti‐T3 mAb in these allospecific clones was inhibited by anti‐T8 mAb in the absence of HLA class I expression on the target cell (Daudi cell line). The hierarchy of blocking with anti‐T8 mAb and the classification of functional epitopes on T8 in anti‐T3‐induced nonspecific cytotoxicity were similar to those obtained in blocking of allospecific reactivity of the CTL clones. This analogy points to an identical function of the T8 antigen in both allospecific and anti‐T3‐induced nonspecific cytotoxicity. If HLA class I molecules are the counter structures of the T8 antigen, then these results argue against an adhesion‐like function of the T8 structure. The combined results show that the T8 molecule has a regulatory role in CTL activation. It is postulated that the T8 antigen might serve as a receptor that transduces a negative feedback signal for T cell activation which prevents T cell triggering by nonspecific interaction.