bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of the bcl‐2 gene in mouse B lymphocytic cell lines is differentiation stage specific
Authors: Gurfinkel Naama , Unger Tamar , Givol David , Mushinski J. Frederic
Published: March 2007

cDNA clones of mouse bcl‐2 have been isolated and characterized by homology to the human bcl‐2 gene, a putative oncogene that is found on the portion of chromosome 18 characteristically involved in the t(14;18) translocation present in nearly all human follicular B cell lymphomas. Our mouse cDNA clone detects 7.9 and 6.3‐kb bcl‐2 RNAs in mouse B cell lymphomas, but only in tumors consisting of pre‐B and follicular center mature B cells, not in pro‐B cell or plasma cell tumors. Thus, this gene appears to be a B cell differentiation marker that is expressed only in committed B cells, but is shut off in end stage plasma cells. This pattern of expression is unique among oncogenes, and we suggest that it may be responsible for the high frequency of translocations at this locus in the common malignancy of human mature B cells, follicular lymphomas.
Specific suppression elicited by EL4 lymphoma cells in syngeneic mice. Specificity includes self‐antigens on EL4
Authors: Grooten Johan , Leroux‐Roel Geert , Fiers Walter
Published: March 2007

In vivo, subclones derived from EL4 lymphoma cells generate suppressor T lymphocytes specific for anti‐EL4 immune responses. Spleen cells of EL4‐sensitized C57BL/6 mice down‐regulate the in vitro induction of EL4‐specific cytolytic T lymphocytes (CTL). In addition, EL4‐sensitized spleen cells interfere with the antigen response of two T lymphocyte clones. These recognize, in an H‐2b context, a self‐antigen on spleen cells that is also expressed by transformed cells, including EL4. The simultaneous anti‐self and anti‐EL4 specificity of the helper and suppressor activities suggests, therefore, that they are the product of an in vivo autoimmune reaction to EL4. The anti‐self suppression might aim to re‐establish self‐tolerance, at the same time down‐regulating responses against immunogenic epitopes that are co‐expressed with the self‐antigen on the EL4 cells. This agrees well with our observation that suppressor T cells, apparently elicited by suppressogenic epitopes on non‐immunogenic EL4 subclones, down‐regulate the CTL response elicited by immunogenic EL4 subclones. The additional self‐specificity of this suppression indicates that the suppressogenic epitopes at least in part represent EL4 self‐antigens.
Mycoplasma‐induced degradation of IgE bound by Fcϵ receptors of rat basophilic leukemia cells
Authors: Chan Bosco M. C. , Froese Arnold
Published: March 2007

Previous studies from this laboratory have shown that Mycoplasma hyorhinis interacts with some unoccupied, high‐affinity 45‐kDa receptors for IgE on rat basophilic leukemia (RBL) cells to induce the formation of 71‐kDa receptors for IgE. The present study demonstrates that when IgE is bound to the high‐affinity receptors, exposure of RBL cells to mycoplasma leads to a time‐dependent degradation of the cell‐bound IgE into fragments of 186 kDa, 158 kDa and 115 kDa, all of which remain bound to the receptors. Upon reduction, these fragments yield 67‐kDa and 55‐kDa ϵ chain‐derived polypeptides. The degradation appears to start at the N‐terminus of the IgE, leading eventually to a complete loss of L chains. In the absence of mycoplasma, the IgE remains relatively intact throughout the same time period with a molecular mass of 210 kDa. The observed degradation of receptor‐bound IgE by mycoplasma, should it also occur in vivo, could have important consequences as far as the IgE‐dependent mediator release is concerned.
Shared idiotopes between anti‐class II monoclonal antibodies and major histocompatibility complex recognition site of T cells
Authors: Tsuji Moriya , Yagi Junji , Abe Ryo , Asano Yoshihiro , Tada Tomio
Published: March 2007

We have raised a number of monoclonal antibodies (mAb) against idiotopes (Id) on monoclonal anti‐murine class II (anti‐Ak or Ek) antibodies. Two anti‐Id mAb among 31 were found to cross‐react with some T cells but not with macrophages and B cells of H‐2k animals. They were able to block syngeneic mixed lymphocyte reaction (SMLR) and antigen‐induced major histocompatibility complex (MHC)‐restricted T cell proliferation of H‐2k but not of other haplotypes. These results indicated that antibodies were recognizing Id associated with the MHC restriction site of T cells. The injection of these anti‐Id mAb into H‐2k mice resulted in the stimulation of self‐class II‐reactive T cell clones as determined by SMLR. They were also able to stimulate in non‐H‐2k strains to prime H‐2k alloreactive T cell clones. Some animals developed anti‐class II (anti‐Iak) antibodies by the injection of anti‐Id. These results indicated that certain anti‐Id (anti‐anti‐class II) antibodies cross‐reacted with T cell receptors which carried class II restriction specificity and were involved in allorecognition. These antibodies were found to have an ability to alter the T cell repertoire in vivo by stimulating such MHC‐restricted clones.
Kinetics of cellular oncogene expression in mouse lymphocytes II. Regulation of c‐fos and c‐myc gene expression
Authors: Schneider‐Schaulies Jürgen , Schimpl Anneliese , Wecker Eberhard
Published: March 2007

Newly isolated lymphocytes from mouse spleens express the c‐fos oncogene even in the absence of mitogen with maximal mRNA levels 60 min post preparation of single cell suspension, whereas c‐myc mRNA levels increase only after mitogenic stimulation with maximal mRNA levels 6 h post stimulation.

The half‐lives of c‐fos mRNA are generally very short; they increase from 14 min (after 30 min of culture) to 70 min (after 2 h of culture). The half‐lives of c‐myc mRNA decrease from 50 min (at 2 and 6 h post stimulation with concanavalin A) to 12 min (at 48 h post stimulation).

The c‐fos gene transcription is already turned on in time‐0 lymphocytes 10 min after disruption of the organ structure of the spleens and is down‐regulated after 2 h and later. In nuclear run‐on experiments with nonstimulated lymphocytes there is already significant transcription of the first exon of c‐myc, but almost no elongation of the transcript to exon 2 and 3. In concanavalin A‐treated lymphocytes elongation is stimulated about 5‐fold within 6 h and returns to background levels at 48 h post stimulation.

The nuclear run‐on analyses of nonactivated lymphocytes showed a signal for RNA complementary to c‐myc mRNA detected with a probe specific for the exon 1/intron 1 boundary of c‐myc, which disappeared with increasing time of concanavalin A stimulation. This anti‐sense transcription may play a role in regulating the elongation of c‐myc transcripts.
Aberrant expression of Ia‐like antigens on tumor cells of regressing but not of progressing Rous sarcomas
Authors: Powell Patrick C. , Hála Karel , Wick Georg
Published: March 2007

Unlike many other tumors, experimentally induced Rous sarcomas in chickens have a definite tendency to regress spontaneously. Regression is under genetic control, but it is immunologically mediated although the target antigens that stimulate an immune response are unknown. Tumor cells in regressing sarcomas were found to express class II major histocompatibility complex (Ia‐like) antigens while tumor cells from progressing sarcomas were negative. This suggests that the induction of Ia‐like antigen expression has a role in the initiation or perpetuation of regression, similar to that postulated for class II antigen expression in a variety of autoimmune diseases.
A new V gene expressed in lambda‐2 light chains of the mouse
Authors: Dildrop Renate , Gause Angela , Müller Werner , Rajewsky Klaus
Published: March 2007

We have partially sequenced the light chain variable regions expressed in three IgM‐producing hybridomas generated from newborn mice or from manipulated animals suppressed for IgM production. In these lines a new V gene (V‐lambda‐X), exhibiting less than 60% homology to any known lambda or kappa V gene, is rearranged to J‐lambda‐2. The light chains produced by these cells contain the lambda‐2 constant domain, but are not recognized by goat antisera raised against conventional mouse lambda light chains.
The continuous antigenic regions in the second domain of the β chain of human MHC DR2 antigen: antigenic profile of the entire extracellular part of the chain
Authors: Atassi Hammad , Ulrich Robert G. , Atassi M. Zouhair
Published: March 2007

Ten consecutive 15‐residue peptides (except for peptide 181–198) that spanned the entire second domain of the HLA DR2 β chain and overlapped by 5 residues were synthesized, purified and characterized. The antibody‐binding activities of the peptides with human alloantisera and with antisera raised in other species were determined by radioimmunosorbent titrations. This established the full profile of peptides having specific antibody‐binding activity with these various antisera. The continuous antigenic sites in this domain were localized within four regions. The localization of the antigenic regions on the second domain completes the description of the antigenic profile of the entire extracellular part of the β chain of HLA DR2. Thus, the continuous antigenic sites on the extracellular part of the DR2 β subunit reside within seven regions with an eighth site being recognized somewhat weakly with some antisera. As was found for the first domain, the immunodominance of a given site varied with the antisera and boundary shifts were present. The submolecular regions recognized on the second domain of the DR2 β were independent of the host species from which the antisera were obtained.
Experimental autoimmune thyroiditis induced by a 5–10‐kDa tryptic fragment from porcine thyroglobulin
Authors: Salamero Jean , Remy Jean Jacques , Michel‐Bechet Marc , Charreire Jeannine
Published: March 2007

Monoclonal autoantibodies obtained using the native porcine thyroglobulin (Tg) molecule for immunization were shown to react against a defined epitope of the Tg molecule. Its biochemical characterization was undertaken, using trypsin treatment of Tg, followed by gel filtration, affinity chromatography, sodium dodecyl sulfate‐poly‐acrylamide gel electrophoresis and high pressure liquid chromatography analysis. Immunoreactivity tested by immunoblotting with appropriate monoclonal anti‐Tg antibody allowed the detection of one peptide fragment of 5–10 kDa, after limited proteolysis with trypsin. We demonstrated that this peptide reacts exclusively with monoclonal anti‐Tg antibodies which block in vitro proliferative T cell response; moreover, the 5–10‐kDa tryptic fragments from porcine Tg were able to induce thyroiditis when injected into normal CBA mice, while porcine Tg depleted from these fragments was not able to do so.
Analysis of the human tonsil B cell repertoire by somatic hybridization: occurrence of both “monospecific” and “multispecific” (auto)antibody‐secreting cells
Authors: Logtenberg Ton , Kroon Ali , Gmelig‐Meyling Frits H. J. , Ballieux Rudy E.
Published: March 2007

The purpose of our study was to investigate the (auto)antibody repertoire of human tonsil B cells. To this end, unseparated tonsil B cells and “large” and “small” tonsil B cells, obtained after fractionation on a discontinuous Percoll gradient, were fused with the (human × mouse) heterohybridoma K6H6/B5. The IgM antibodies secreted by individual clones were analyzed in spot‐enzyme‐linked immunosorbent assay for reactivity against a panel of 5 autoantigens and 1 xenoantigen. The results show that both “mono‐” and “multispecific” (auto)antibody‐secreting clones can be obtained by somatic hybridization of unseparated, “small” and “large” tonsil B cells. The patterns of IgM reactivities in these three collections of hybridomas did not differ significantly. Inhibition experiments revealed that “multispecific” antibodies can bind with high affinity to more than one (auto)antigen. The results of these experiments are discussed in relation to the state of activation of tonsil B lymphocytes.
Nickel‐specific T lymphocyte clones derived from allergic nickel‐contact dermatitis lesions in man: heterogeneity based on requirement of dendritic antigen‐presenting cell subsets
Authors: Kapsenberg Martien L. , Res Peter , Bos Jan D. , Schootemijer Annelies , Teunissen Marcel B. M. , Van Schooten Wim
Published: March 2007

Inflammatory skin T cells were cloned in an antigen‐independent way from lesions of patients with experimentally induced nickel‐contact dermatitis. In three experiments 7–15% of the CD4+8− T lymphocyte clones (TLC) appeared to be specific for nickel in a proliferation assay. These proliferative response of nickel‐specific TLC required the presence of antigen‐presenting cells (APC) and were restricted by HLA class II molecules. All TLC recognized nickel presented by APC from epidermal skin. Remarkably, 5 out of 8 nickel‐specific TLC exclusively recognized nickel when presented by these skin‐specific APC whereas 3 out of these 8 clones could also recognize nickel presented by APC from peripheral blood. The critical APC within the fractions of epidermal cells and peripheral blood appeared to belong to the family of dendritic cells, i.e. Langerhans cells and circulating dendritic cells, respectively.
A new T helper cell specificity within the pigeon cytochrome c determinant 95–104
Authors: Carbone Francis R. , Staerz Uwe D. , Paterson Yvonne
Published: March 2007

A T cell hybridoma with unusual antigen specificity has been isolated from B10.BR mice immunized with pigeon cytochrome c. Using synthetic peptide analogues of the pigeon cytochrome c T cell determinant 81–104 we have determined that this hybridoma is specific for residues within the sequence 95–104. However, the mode by which this T cell hybridoma recognizes this determinant in the context of the I‐Ek molecule differs from all previously described T cell clones in that it is not stimulated by the moth cytochrome c analogue 81–103.
Alternative pathway of complement activation by stimulated T lymphocytes. II. Elevation of cytotoxic potential against complement receptor‐carrying cell lines
Authors: Ramos Oscar F. , Sármay Gabriella , Eggertsen Gösta , Nilsson Bo , Klein Eva , Gergely János
Published: March 2007

Exposure of lectin‐stimulated (concanavalin A, phytohemagglutinin and pokeweed mitogen) blood lymphocytes to human serum or to purified C3 increased their cytotoxic capacity towards complement receptor positive targets such as Raji and Daudi cells. The lysis of complement receptor‐negative lymphoblastoid cell lines was not influenced. The lytic capacity of lymphocytes exposed to 12‐O‐tetradecanoylphorbol 13‐acetate was not elevated by human serum. Lectin‐stimulated lymphocytes were previously shown to activate and bind C3. The results using lymphocytes activated in different ways and targets with or without complement receptor expression suggest that the C3b deposited on lymphocytes binds to the complement receptor on the targets. This contact elevates the avidity between the two cells as indicated also by the increased frequency of the lymphocyte‐target conjugates. On the basis of immune adherence the C3 fragment bound on the lymphocytes was identified as C3b. The increase of the conjugate formation and cytotoxicity was abrogated when the target cells, Raji, were pre‐exposed to purified C3d which occupy the CR2 receptor. The majority of lymphocytes responsible for the cytotoxicity were CD8+.
In vivo generation and function of B cells in the presence of a monoclonal anti‐IgM antibody: implications for B cell tolerance
Authors: Gause Angela , Yoshida Nobuaki , Kappen Claudia , Rajewsky Klaus
Published: March 2007

C57BL/6 mice were chronically treated with milligram doses of the noncytotoxic monoclonal anti‐μb antibody MB86 (IgG1,x) from birth or from fetal life. The spleens of the manipulated animals contained large numbers (25% as compared to control mice) of B lineage cells which expressed IgMb on the surface after overnight incubation in vitro. The spleens also contained B cells whose surface IgM was unreactive with antibody MB86. A few such cells were immortalized by cell fusion. They included cells secreting μ together with λ2 chains which apparently prevent recognition by antibody MB86, and a point mutant in the first constant domain of the μ chain, changing the b to the a allotype. Cells expressing MB86− surface IgM did not selectively expand under MB86 treatment over the first few months of life.

Serum Ig levels in the manipulated mice were normal except for IgM which was undetectable in most instances. In some animals low levels of MB86− IgM molecules were produced. At 7 weeks of age, mice treated with MB86 from birth produced normal‐size IgG anti‐(4‐hydroxy‐3‐nitrophenyl)acetyl (NP) responses with the usual predominance of λ1 chain‐bearing IgG1 antibodies. At the age of 5–6 months, and also in young mice treated with MB86 from fetal life, the responses were variable and presumably oligoclonal, with a tendency towards the production of antibodies with γ3 heavy and λ2 or λ3 light chains. We interpret these results to mean that B cells hit by antibody MB86 from the time of their generation become unresponsive to T cell‐dependent stimulation, but are still able to expand. Occasionally, they escape functional suppression through class switching (to IgG3) upon mitogenic stimulation. At birth, C57BL/6 mice contain a mature B cell population which mediates normal immune responses under MB86 treatment and eventually dies out.

Taken as a model of tolerance induction in B cells, the data provide evidence for “tolerant” cells and support the concept of an early phase of sensitivity to tolerance induction in B cell differentiation.

The anti‐NP response under MB86 treatment differed profoundly from control responses in idiotypic terms, but became normal as the animals recovered from suppression. This may reflect blockade by MB86 of idiotypic selection within the B cell population.
Multiple HLA class I‐dependent cytotoxicities constitute the “non‐HLA‐restricted” response in infectious mononucleosis
Authors: Strang George , Rickinson Alan B.
Published: March 2007

Primary Epstein‐Barr virus (EBV) infection, when manifest as infectious mononucleosis (IM), induces a broad‐ranging and apparently non‐HLA‐restricted cytotoxic response whose nature has not been resolved. In the present experiments the ability to cryo‐preserve IM mononuclear cell preparations, after depletion of CD16+ natural killer cells, has allowed detailed analysis of the response on appropriately constructed target cell panels. The results show that IM effector preparations are polyclonal with separate HLA class I antigen‐dependent reactivities against (a) the autologous EBV‐transformed lymphoblastoid cell line (LCL) and (b) particular HLA class I‐mis‐matched LCLs. The autologous LCL‐directed response shows the hallmarks of immunologically specific T cell cytotoxicity; only EBV+ B cell blasts are recognized and the interaction can be blocked by monoclonal antibodies to CD3 and CD8 on the effector cell surface and to HLA class I antigens on the target cell. Such findings demonstrate, for the first time, that the primary cytotoxic response to EBV infection includes a virus‐specific HLA‐restricted component like that found in the T cell memory of persistently infected individuals. Separate components of the response are preferentially active against some (but not all) HLA‐mismatched LCLs, the pattern of reactivity being distinct for each individual IM patient and reproducible on repeated testing. Monoclonal antibody blocking experiments show that these HLA‐mismatched interactions also involve CD3 and CD8 antigens on the effector cell and HLA class I antigens on the target cell. Where tested, such lysis affected both EBV+ and EBV− B cell blasts from the relevant HLA‐mismatched donors. We postulate that a widespread primary infection of the B cell system by EBV leads to a generalized expansion not just of the virus‐specific response but also of other T cell responses coincidentally active at the time. The unusual activity of IM effector preparations against HLA‐mismatched LCLs arises from fortuitous cross‐recognition of allogeneic cells by immunologically specific cytotoxic T cell clones coincidentally expanded in vivo alongside the EBV‐specific response.
Class I H‐2Db determinants are not involved in hybrid resistance to parental H‐2b/Hh‐1b bone marrow allograft
Authors: Milisauskas Vita K. , Kaminsky Steven G. , Nakamura Ichiro
Published: March 2007

Hybrid resistance to parental H‐2b bone marrow grafts is directed to a cell surface structure controlled by the Hh‐1 locus in or near the H‐2D region. The nature of this surface structure is not known. Since homozygosity at the class I H‐2D locus or loci in this haplotype would seem a necessary but not sufficient condition for the grafts' susceptibility to resistance, we tested whether the expression of this phenotype is dependent on the expression of class I H‐2Db determinants. Cloned variants of H‐2b tumor RBL‐5 were obtained by immunoselection for the absence of H‐2Db expression, as determined by the inability to bind specific antibody and to induce or react with alloreactive cytotoxic T lymphocytes. The three clones used in this study were H‐2Db negative but H‐2Kb positive and were natural killer cell resistant. When tested in vivo as competitive inhibitors the variant cells were capable of blocking hybrid resistance to parental H‐2b bone marrow grafts as were unselected H‐2Db‐positive parental line cells. Therefore, H‐2Db expression is irrelevant for Hh‐1b expression. An incidental observation was that YAC‐1 cells, a non‐H‐2b tumor with pronounced susceptibility to natural killing, were able to block hybrid resistance. This reactivity, not observed in our previous studies, raises the possibility that at least some of the effector cells are cross‐reactive or capable of dual recognition.
CD3+ WT31− peripheral T lymphocytes lack T44 (CD28), a surface molecule involved in activation of T cells bearing the α/β heterodimer
Authors: Poggi Alessandro , Bottino Cristina , Zocchi Maria Raffaella , Pantaleo Giuseppe , Ciccone Ermanno , Mingari Cristina , Moretta Lorenzo , Moretta Alessandro
Published: March 2007

We have applied two‐color fluorescence cytofluorometric techniques to the analysis of the distribution of T44 and CD3 antigens in peripheral blood human lymphoctes. While most CD3+ cells co‐expressed T44 antigen, a small distinct subset was CD3+ T44− (2–10% of CD3+ cells). This cell subset also did not react with the WT31 monoclonal antibody (mAb), specific for an α/β framework determinant of the T cell receptor (TCR). Lack of T44 antigen expression was also observed in purified CD3+ WT31− polyclonal populations that had been cultured in medium containing interleukin 2 (IL2) and as well as >30 clones expressing the CD3+4−8−WT31− surface phenotype. Immunoprecipitation experiments confirmed that expression of T44 molecules was confined to CD3+ WT31+ peripheral blood T cells. While conventional CD3+ WT31+ cells produced IL2 in response to mAb directed to CD2, CD3 or T44 surface molecules, CD3+ WT31− cells did not respond to anti‐T44 mAb but released IL2 following stimulation with anti‐CD2 or anti‐CD3 mAb. Therefore, assuming that anti‐T44 mimicks the effect of a still undefined natural ligand our data suggest that T cells expressing the γ‐gene surface product may be signalled by stimuli which differ, at least in part, from those acting on CD3+ WT31+ T lymphocytes.
Lysis of nonnucleated red blood cells by cytotoxic T lymphocytes
Authors: Lanzavecchia Antonio , Staerz Uwe D.
Published: March 2007

To establish the role of direct membrane damage in cytotoxic T lymphocyte (CTL)‐mediated lysis we investigated whether CTL would be capable of lysing nonnucleated target cells. By antibody‐mediated targeting we show that CTL are indeed capable of lysing sheep and human red blood cells.
Phorbol 12‐myristate 13‐acetate induces surface expression of T3 on human immature T cell lines with and without concomitant expression of the T cell antigen receptor complex
Authors: Carrel Stefan , Mach J.‐P. , Miescher Guido , Salvi Suzanne , Giuffrè Laura , Schreyer Magali , Isler Patrick
Published: March 2007

The T3 complex is known to be expressed on the cell surface of mature T cells together with either the α‐β heterodimeric T cell receptor (TCR) or the TCR γ protein. In a number of immature T cell malignancies, however, T3 has been described exclusively in the cytoplasm. We have investigated five such T cell lines with cytoplasmic T3 and could demonstrate by biosynthetic labeling the presence of the α and β chains of the TCR in the cytoplasm of two of them, CEM and Ichikawa. No surface TCR α‐β protein could be detected by staining with the WT31 antibody. These observations, therefore, argue against the concept that expression of the TCR α chain controls the surface expression of the T3/TCR complex. Interestingly, phorbol 12‐myristate 13‐acetate (PMA) induced cell surface expression of T3 protein in these two cell lines only. Moreover, on surface‐iodinated CEM cells no association of T3 and TCR molecules could be demonstrated after treatment with PMA, and expression of TCR α and β chains was limited to the cytoplasm. In Ichikawa cells, however, PMA induced surface expression of a mature T3/TCR complex. Our findings indicate that separate regulatory mechanisms may exist for the surface expression of the T3 proteins and for the assembly of the T3/TCR complex.
Analysis of T cell‐replacing factor‐like activity: potent induction of T helper activity for human B cells by residual concanavalin A and interleukin 2
Authors: Sauerwein Robert W. , Van Der Meer Walter G. J. , Aarden Lucien A.
Published: March 2007

At least two factors with the capacity to induce IgM synthesis in human B cells were found to be present in the 15–20‐kDa fraction of the supernatant of mononuclear cells activated with concanavalin A (Con A) and phorbol ester. Previously, it has been shown (Sauerwein, R. W. et al., Eur. J. Immunol. 1985. 15: 611) that interleukin 2 (IL 2) in this material is able to induce T cell‐dependent IgM secretion in normal B cells. Evidence was obtained for the presence of another factor distinct from IL 2 that could replace T cells in the induction of B cell differentiation. We have analyzed this factor with the use of a neoplastic B cell population of prolymphocytic origin that was functionally nonresponsive to IL 2. T cell‐replacing factor (TRF)‐like activity and IL 2 could be separated by ion‐exchange chromatography, although a small amount of IL 2 was recovered in the TRF fractions. This small amount of IL 2 was found to be crucial for the observed TRF activity. Moreover, a substantial amount of monomeric Con A was detected in the TRF preparation. Our studies show that Con A in the presence of IL 2 can act as a potent inducer of helper function in lower numbers of T cells for normal and neoplastic B cells. Functional assays for T cell contamination in B cell suspensions are therefore of limited value because they are determined by the efficiency of the stimulating signal. Particularly in those B cell factor preparations, obtained from mitogen‐activated T cells with an obligatory or unidentified role of IL 2, the possible effect of a contaminating mitogen must be considered.
Interferon‐γ restores T lymphocyte proliferation of nonresponders to IgG1 anti‐CD 3 via the induction of Fcγ1 receptors on monocytes
Authors: Benichou Gilles , Kanellopoulos Jean M. , Wallon Christine , Boue François , Delfraissy Jan‐François
Published: March 2007

Human peripheral blood T lymphocytes are stimulated to grow and divide by some mouse anti‐CD 3 monoclonal antibodies. This polyclonal mitogenesis is dependent on both their immunoglobulin subclass and the presence of monocytes. The unresponsiveness of T lymphocytes from certain individuals to mouse IgG1 (or IgG2a) antibodies is due to a failure of their monocytes to bind these IgG isotypes.

In this study, we have selected such nonresponder subjects to IgG1 anti‐CD 3 (UCHT 1) in order to study their monocytes. Two assays were used: IgG1 and IgG2 EA rosettes to evaluate their Fc receptor‐binding capacity, and IgG‐mediated monocyte chemiluminescence to test their receptor‐related activation since mouse anti‐T cell antibodies binding to lymphocytes trigger monocyte chemiluminescence via their Fc receptor.

We have observed that in all nonresponder subjects the absence of IgG1 anti‐CD 3 monocyte chemiluminescence strictly correlates with the absence of IgG11 EA rosettes. Thus, the failure to respond to UCHT 1, in all nonresponders tested to date, is due to the absence of Fcγ1 receptors on their monocytes. Treatment of nonresponder monocytes by recombinant interferon‐γ was shown to restore T cell proliferation and monocyte chemiluminescence in nonresponders. This effect of interferon‐γ correlates with the appearance of Fcγ1 receptors on monocytes from these individuals. This work strongly suggests that nonresponder monocytes possess functional genes for Fcγ1 receptors which are not expressed normally at a detectable level but can be induced by interferon‐γ.
Epstein‐Barr virus‐transformed human precursor B cell lines: altered growth phenotype of lines with germline or rearranged but nonexpressed heavy chain genes
Authors: Gregory Christopher D. , Kirchgens Christa , Edwards Carole F. , Young Lawrence S. , Rowe Martin , Forster Alan , Rabbitts Terence H. , Rickinson Alan B.
Published: March 2007

A series of lymphoblastoid cell lines (LCLs) have been established by in vitro infection of fetal bone marrow and fetal liver cells with Epstein‐Barr virus (EBV). While most lines showed the usual mature B cell phenotype, a small proportion were cytoplasmic and surface immunoglobulin (Ig) heavy and light chain negative. Analysis of gene rearrangements indicated that the Ig lines were either germ‐line or nonproductively rearranged when probed for JH and were in germ‐line configuration for Cx; no μ or χ mRNA could be detected in such cells. Precursor B cell lines were indistinguishable from their normal Ig+ counterparts in their expression of a wide variety of cell surface markers including “activation” antigens usually associated with the lymphoblastoid state; even the single LCL showing germ‐line heavy and light chain genes expressed B lineage‐specific cell surface antigens. However, the Ig− lines were distinct from their Ig+ counterparts in three important respects: (a) they grew much more slowly and achieved lower saturation densities, (b) they showed unusually high proportions (8–16%) of cells in EBV‐productive cycle, and (c) they contained unusually high proportions (up to 40%) of cells expressing free joining (J) chain. These results suggest that precursor B cells differ in their response to the growth‐transforming effects of EBV such that the virus‐cell interaction in precursor B cell lines is inherently less stable than in conventional LCL. In particular there may be a greater movement of cells out of cycle and along the B cell maturation pathway. It is possible that such movement leads in individual cells either to virus replication or to a “sterile” plasmacytoid differentiation with J chain expression in the absence of Ig synthesis.
Anti‐anti‐IgE idiotypic antibodies mimic IgE in their binding to the Fcϵ receptor
Authors: Baniyash Michal , Eshhar Zelig
Published: March 2007

The binding site of some anti‐idiotypic antibodies (anti‐Id) can appear as a structural image of the antigen and as such may mimic its biologic activity. We raised anti‐anti‐IgE antibodies in an attempt to obtain anti‐Id capable of interacting with the Fcϵ receptor (FcϵR). Guinea pigs were immunized with purified murine monoclonal antibodies (mAb) that had been found to react with epitopes closely related to the site on the IgE molecule which is recognized by the FcϵR. After only two injections, we could detect in the immune sera anti‐Id that inhibited the binding of IgE to the anti‐IgE mAb used as immunogens. However, only after 10 immunizations over a period of about 6 months could we detect antibodies that competed efficiently with the binding of IgE to rat basophilic leukemia (RBL) cells. The “IgE‐like” anti‐Id could be affinity purified from immunosorbents made of the anti‐IgE mAb. F(ab′)2 and Fab′ fragments were as effective inhibitors of IgE binding as the intact anti‐anti‐Id antibodies. Some of the anti‐Id caused RBL degranulation and all of them, like IgE, inhibited the binding of specific anti‐FcϵR mAb to RBL cells. In summary, by hyperimmunization with anti‐IgE mAb we could obtain anti‐Id whose antigen‐binding site is recognized by the mast cell receptor specific to the Fc portion of IgE.
Transcription of a T cell receptor β chain gene in L cell fibroblasts following DNA‐mediated gene transfer
Authors: Sensi Marialuisa , Dembić Zlatko , Steinmetz Michael
Published: March 2007

Functionally rearranged T cell receptor α and β‐chain genes from a fluoresceinspecific cytotoxic T cell clone have been introduced, together with the selectable marker gene neo, into mouse fibroblasts (L cells) by electroporation. Transformed cells were selected for neo gene expression by growth in medium containing the antibiotic G418. Southern blot analysis of DNA from transformed L cell clones revealed that the endogeneous T cell receptor α and β‐chain genes were in germ‐line configuration and that in 4 of the 6 clones examined the exogenously introduced rearranged α and β chain genes were present. The introduced β‐chain gene is transcriptionally active in two L cell clones examined whereas no transcription of the α‐chain gene could be detected in the same transformants.
High‐affinity binding sites for human 26‐kDa protein (interleukin 6, B cell stimulatory factor‐2, human hybridoma plasmacytoma growth factor, interferon‐β2), different from those of type I interferon (α,β), on lymphoblastoid cells
Authors: Coulie Pierre G. , Vanhecke Alain , van Damme Jo , Cayphas Sylvie , Poupart Pascale , De Wit Luc , Content Jean
Published: March 2007

The human 26‐kDa glycoprotein (26K) is a cytokine produced by lymphoid as well as nonlymphoid cells. So far it is active as (a) a potent hybridoma and plasmacytoma growth factor on mouse cells, (b) a B cell differentiating factor on human cells, and (c) (for some authors) an interferon (IFN). Internally labeled recombinant human 26K, obtained by translation of mRNA in Xenopus oocytes, was used to investigate the presence of specific receptors for this new cytokine and to analyze its binding to responsive cells. The results indicate that (a) the 26K‐responsive human lymphoblastoid CESS cells express about 1500 high‐affinity (Kd = 30 pM) binding sites for this cytokine, (b) this binding is not competed for by interleukin (IL)1, IL2, tumor necrosis factor (TNF), IFN‐α2, IFN‐β or IFN‐γ, and (c) these 26K‐binding sites are different from the classical type I (α‐β) IFN receptors by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis.
A phenotypically dominant regulatory mechanism suppresses major histocompatibility complex class II gene expression in a murine plasmacytoma
Authors: Venkitaraman Ashok R. , Culbert Eric J. , Feldmann Marc
Published: March 2007

The expression of major histocompatibility complex (MHC) class II antigens is down‐regulated when B cells differentiate into plasma cells. We have studied the mechanism of down‐regulation of MHC class II expression in a BALB/c strain‐derived murine plasmacytoma cell line, NS1. NS1 cells express MHC class I antigens but not MHC class II antigens. We tested 20 uncloned hybrid cell lines obtained from the fusion of NS1 cells with MHC class II‐expressing splenic B cells prepared from CBA, SJL or BALB/c mice. All the hybrid cell lines expressed MHC class I antigens of either or both parental haplotypes but did not express MHC class II. One NSI × splenic B cell hybrid clone, K3, was used to further validate these results; K3 cells expressed MHC class I but not MHC class II antigens. K3 was fused to the MHC class II‐expressing B lymphoma A20, and the seven resulting hybrid cell lines were again found to express MHC class I but not MHC class II antigens. Since NS1 is a subclone of the P3‐X63Ag8 murine plasmacytoma, we also tested one P3‐X63Ag8 × splenic B cell hybrid, Sp2/0, and two Sp2/0 × splenic B cell hybrids. All were found to express the appropriate MHC class I antigens but did not express MHC class II. Thus, our results suggest that the NS1 plasmacytoma suppresses MHC class II expression by a phenotypically dominant regulatory mechanism. We found that NS1 cells express correctly sized mRNA for the MHC class II genes Aα, Eα and the invariant chain. The co‐expression of MHC class I protein and I‐A and I‐E region gene transcripts provides strong evidence that the MHC gene cluster is structurally intact, and that lack of class II expression is due to a genetic regulatory mechanism. The amounts of class II mRNA expressed by NS1 cells were at least equivalent to those found in splenic lymphocytes. Therefore, this regulation must operate post‐transcriptionally.
Correlation of T cell receptor gene rearrangements to T cell surface antigen expression and to serum immunoglobulin level in scid mice
Authors: Habu Sonoko , Kimura Minoru , Katsuki Motoya , Hioki Kyoji , Nomura Tatsuji
Published: March 2007

The severe combined immunodeficient (scid) mouse which has undetectable serum immunoglobulin (Ig) contains a small number of thymic lymphocytes which express Thy‐1 and IL 2 receptors (IL 2R) but not Lyt‐2 or L3T4 molecules. These thymocytes did not show any rearrangement of T cell receptor (TCR) β‐chain genes. Such thymocyte characteristics in the scid mouse were similar to the 15‐day embryonic thymocytes in ordinary mice, indicating that the scid mouse thymocytes are arrested in the early stage of intrathymic differentiation. However, low or medium level serum Ig was occasionally found in the littermates of the scid mouse. The thymocytes of these mice showed some evidence of TCR β‐chain gene rearrangement and the presence of Lyt‐2+/L3T4+ cells in correlation with the serum Ig level. In the mice with some serum Ig the thymocyte cell number was increased and the proportion of IL 2R+ cells was decreased. Collectively, these results suggest that the rearrangement of TCR β‐chain genes is associated with the expression of Lyt‐2 and L3T4 molecules in intrathymic differentiation and probably with cell proliferation of the migrated lymphoid cells in the scid mouse.
Transient gene expression in untransformed lymphocytes
Authors: Mårtensson Inga‐Lill , Leanderson Tomas
Published: March 2007

Conditions for transfection of normal, freshly isolated and mitogen‐stimulated spleen cells were established. A sharp optimum of plasmid at 10 μg per 1.5 × 107 transfected spleen cells per transfection was observed. The Ig promoter and the IgH enhancer activity was found to be restricted to cells of the B lineage also in normal, freshly isolated lymphocytes in vitro.
The internal image‐like anti‐idiotypic response to a CD3‐specific monoclonal antibody in primates is dependent on the T cell‐binding properties of the injected antibody
Authors: Jonker Margreet , Nooij Frans J. M.
Published: March 2007

Murine monoclonal antibodies used for therapeutic purposes generally elicit a strong antibody response. A large proportion of this response is specific for the idiotype of the injected monoclonal antibody. The CD3 T cell antigen is polymorphic in rhesus monkeys. A monoclonal antibody, FN18, which detects this polymorphism was used to analyze the immune response to FN18 in FN18+ and FN18− animals. The results of this study show that the internal image‐like anti‐idiotypic response predominantly occurs in FN18+ animals. This suggests that this type of anti‐idiotypic response is limited to cell‐binding monoclonal antibodies.
Evidence for a mutual influence of idiotype‐expressing donor cells and recipient lymphocytes in neonatal hosts
Authors: Bösing‐Schneider Rita , Selinka Hans‐Christoph
Published: March 2007

Nonirradiated recipients do not permit activation of transferred syngeneic lymphocytes. This transplantation barrier gives us insight into the mechanism of the regulatory circuits of the donor's and host's immune network. The present report demonstrates that this barrier depends on the state of differentiation of cells from both donor and host. We measured the expression of anti‐α(1–3)dextran (Dex) correlated idiotypes by cells from responder BALB/c animals (allotype Ig, Dex+, IdDex+) in nonresponder (IgbH, Dex−, IdDex−) congeneic mice. Adult IgbH recipients did not permit activation of either adult spleen or bone marrow cells (isogeneic barrier). Neonatal recipients showed functional tolerance towards adult spleen cells. By contrast, neonates neither permited activation of adult B cell‐depleted bone marrow cells, nor of neonatal immature spleen cells. The results show that the immature system of the neonate is permissive towards mature (adult) congeneic lymphocytes, but not towards immature cells from congeneic neonates or adult bone marrow. It appears that mature adult cell populations are dominant in the immature neonatal host. However, the time required by transferred immature cells to differentiate in the neonatal recipient concomitantly allow the latter to gain maturity and functionally reject the grafted cells.
Xenogeneic recognition of soluble and cell surface HLA class II antigens by proliferative murine T cells
Authors: Viguier Mireille , Lotteau Vincent , Charron Dominique , Debré Patrice
Published: March 2007

In order to characterize the murine anti‐human xenogeneic mixed lymphocyte reactions (MLR), we studied T cell proliferative responses against various human lymphoid cells by immunization of mice either with cellular or purified HLA‐DR antigens. Data presented here indicated that small amounts of soluble HLA‐DR antigen were able to prime mice, and that the xenogeneic MLR depends on the expression of HLA class II antigens on the stimulating cells. Experiments using a mutant call line clearly showed that HLA‐DP molecules were also sufficient in eliciting a primary or a secondary xenogeneic MLR while no secondary proliferative response was obtained with cells expressing only HLA class I molecules.

Using a large panel of human cells with various haplotypes, our results also showed that (a) nonpolymorphic determinants of HLA class II antigens trigger dominantly the murine T cells and (b) the xenogeneic response required I‐E and L3T4 accessory molecules and was not inhibited with anti I‐A and monomorphic anti‐HLA class II antigen monoclonal antibodies. Altogether these results suggest that HLA class II antigens act as nominal antigens in triggering a murine anti‐human proliferative response.
T cell activation by processed antigen is equally blocked by I‐E and I‐A‐restricted immunodominant peptides
Authors: Lakey Ellen K. , Casten Lisa A. , Anderson Mark S. , Smolenski Lori A. , Smith John A. , Margoliash Emanuel , Pierce Susan K.
Published: March 2007

The T cell response to a soluble protein requires the processing of the native antigen by an antigen‐presenting cell (APC) to a peptide containing an antigenic determinant, which is transported to and bound on the antigen‐presenting cell surface, where it is subsequently recognized by the specific T cell in the context of the appropriate Ia molecule. Investigating the response of a pigeon cytochrome c‐specific, I‐Ek‐restricted T cell hybrid, which recognizes a determinant present within a 10‐amino acid C‐terminal fragment of the protein, it was previously demonstrated that peptides homologous to the peptide from pigeon cytochrome c, but which were not stimulatory, blocked the T cell response to pigeon cytochrome c as processed and presented by APC. In this report the ability of a series of fourteen, 20‐amino acid overlapping peptides, representing the entire length of staphylococcal nuclease (Nase), were assessed for their ability to block the response of a pigeon cytochrome c‐specific T cell hybrid to antigen‐pulsed presenting cells. Only three Nase peptides blocked the I‐Ek‐restricted pigeon cytochrome c‐specific T cell response. Two of these, Nase 61–80 and Nase 91–110, function as T cell antigens in the I‐Ad and I‐Ab‐restricted response to Nase. The third blocking peptide, Nase 101–120, has not been shown to be a T cell antigen. Two other peptides, Nase 51–70 and Nase 81–100, which are recognized by Nase‐specific T cells in the context of I‐Ek, have no effect on the I‐Ek‐restricted cytochrome c‐specific T cell response. None of these peptides block the higher affinity, heteroclitic response of pigeon cytochrome c‐specific T cells to tobacco hornworm moth cytochrome c. Moreover, the response of an I‐Ak‐restricted T cell to ovalbumin was blocked by the I‐Ek‐restricted cytochrome c peptides from three different species. Thus, peptides with no obvious primary amino acid sequence homology, and which are not capable of being recognized in the context of the same Ia, compete with one another for the sites on the APC necessary for presentation of processed antigen to T cells. These results suggest that there are structures on the APC surface in addition to Ia, which are necessary for effective antigen presentation following processing. One suitable candidate for such a cell surface material is the recently identified peptide‐binding protein, PBP72/74 (Lakey et al., Proc. Natl. Acad. Sci. USA 1987. 84: 1659).
Antigen‐specific T cell unresponsiveness in cloned helper T cells mediated via the CD2 or CD3/Ti receptor pathways
Authors: Lamb Jonathan R. , Zanders Edward D. , Sewell William , Crumpton Michael J. , Feldmann Marc , Owen Michael J.
Published: March 2007

We have investigated the role of the CD2 protein in the negative regulation of immune function and report that similar to antigen and anti‐CD3, the monoclonal anti‐CD2 antibodies (T112 and T113) can induce specific unresponsiveness. Antigen and anti‐CD2 tolerogenic signals both down‐regulated the phenotypic expression of CD3‐Ti. In contrast CD2 surface expression was up‐regulated after exposure to peptide and down‐regulated after anti‐T112 and T113 preincubation. However, in both instances interleukin 2 receptor surface levels were increased. These phenotypic changes could only be partly explained by variations in the levels of the transcripts encoding the CD3‐Ti and CD2 molecules.
A novel strategy for immunotherapy using antibody‐coupled carriers to focus cytotoxic T helper cells
Authors: Ochi Atsuo , Worton Katharine S. , Woods Greg , Gravelle Micheline , Kitagami Keiji
Published: March 2007

Targeting of cytotoxic T cells to cell‐bound antigens has previously been reported using bispecific antibodies. In this report we document a novel targeting system whereby cytotoxic T helper (Thc) cells were targeted to a B cell lymphoma by means of an anti‐idiotypic antibody (anti‐Id), specific for the surface immunoglobulin of the B cell, coupled to the carrier protein keyhole limpet hemocyanin (KLH). In this system the anti‐Id‐KLH complex bound to the Id determinant of the surface immunoglobulin of the B cell lymphoma. This complex was then presented in a major histocompatibility complex class II‐restricted manner to the KLH‐specific Thc cell (KLH55) which was induced into its cytolytic pathway through the specific recognition of KLH. The uniqueness of this system was that it utilized the inherent ability of the target B cell to process and present antigen. This offered the distinct advantage that processed antigen re‐expressed on the cell membrane was in a more stable form, thereby enabling the target cell to remain susceptible to cytotoxicity for an extended period of time. Furthermore, as is characteristic of Thc cells in general, bystander kiling was demonstrated and Id (or Ia)‐negative mutants of the target cell did not escape destruction. The adaptation of such a system will have useful implications for future immunotherapeutic strategies.