bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterization of two human monoclonal IgM antibodies that recognize nuclear lamins
Authors: Lassoued KaïS , André Chantal , Danon Francoise , Modigliani Robert , Dhumeaux Daniel , Clauvel Jean‐Pierre , Brouet Jean‐Claude , Courvalin Jean‐Claude 
Published: March 2007

AbstractUsing immunofluorescence and immunoblotting techniques, we have identified monoclonal IgM λ from two patients that are specific for lamins A and C and lamin B, respectively. Lamins A, B, and C are peripheral membrane proteins of the nuclear envelope with structural similarities to cytoplasmic intermediate filament proteins. When studiedby indirect immunofluorescence on rat tissues, the serum containing anti‐laminB IgM stained smooth and striated muscles in addition to nuclear envelopes. Lamin B antibodies affinity purified from this serum were able to label muscle cells, suggesting that lamin B shares an epitope(s) with an unidentified muscular component(s). Since in an enzyme‐linked immunosorbent assay there was no reactivity with a panel of proteins which are frequent targets of “natural” antibodies, these monoclonal IgM appear to belong to the rare category of IgM that possess a restricted specificity.
Spontaneous and ligand‐induced endocytosis of CD23 (Fcϵ receptor II) from the surface of B lymphocytes generates a 16‐kDa intracellular fragment
Authors: Grenier‐Brossette Nicole , Bourget Isabelle , Akoundi CaméLia , Bonnefoy Jean‐Yves , Cousin Jean‐Louis 
Published: March 2007

AbstractIt has been reported that the 45‐kDa low‐affinity Fcϵ receptor (FcϵRII) on B cells is cleaved spontaneously from the cell surface to release soluble fragments. This study demonstrates an additional fate of the FcϵRII. 125I‐labeled CD23+ B cells were cultured for 24 h at 37°C. After lysis, cell extracts were immunoprecipitated with CD23 monoclonal antibodies. Using this methodology, we demonstrated that an increasing amount of the labeled FcϵRII becomes progressively resistant to externally applied trypsin, indicating that a fraction of the cell surface receptors are internalized. In parallel, a labeled 16‐kDa material, recognized by CD23 monoclonal antibodies directed to the lectin‐like domain of the Fcϵ‐RII appears inside the cells. Chloroquine does not affect internalization of the FcϵRII, but completely abolishes the formationof the intracellular fragment, suggesting that the receptor is processed by proteolyticcleavage inacidic organelle. In addition, the internalization is enhanced in the presence of CD23 monoclonal antibodies. These data demonstrate that FcϵRII can be internalized by ligand‐induced endocytosis and subsequently cleaved in an intracellular compartment. These results also support the view that the FcϵRII is involved in antigen focusing and antigen presentation.
Thymic hyperplasia in transgenic mice caused by immortal epithelial cells expressing c‐kit ligand
Authors: Moll JüRgen , Eibel Hermann , Schmid Peter , Sansig Gilles , Botteri Florence , Palacios Ronald , Putten Herman Van Der 
Published: March 2007

AbstractTo dissect mechanisms that co‐ordinate specific events in thymopoiesis we have characterized alterations in thymic structure and function caused by expression of atransgene. This gene encodes SV40Tag and is specifically expressed in a subset of thymicepithelial (TE) cells around birth. As a result the number of immortal TE cells increases, thymic mass increases (up to 3 g), and thymopoiesis is expanded. The latter is reflected by a ˜ 100‐fold increase of the major thymocyte subsets and increased peripheral T cell counts. Grossly hyperplastic thymi retain many but not all morphological features of a normal thymus. Also in grafts, SV40Tag+ TE cells steer expansion (up to 8 g) and organize a tissue with mainly cortex‐like featuresthat includes mainly SV40Tag+ TE cells, thymocytes, and macrophages. To investigate expression of specialized gene functions in the immortal TE cells, a cell line was derived. The Epi‐A1 cell line expresses the genes for major histocompatibility complex class I and II, Thy‐1, interleukin (IL)‐6, IL‐7, macrophage‐colony‐stimulating factor, and transforming growth factor‐β3. Most importantly, Epi‐A1 cells also express the IL‐4 receptor and the c‐kit ligand (KL), a factor that, in concert with commitment factors, channels progenitors into hemopoietic lineages. The expression of low constitutive levels of KL mRNA does not require IL‐4, but KL mRNA levels are increased dramatically in response to IL‐4. Since constitutive expression of KL mRNA in vivo is restricted to a small subset of TE cells in the thymus, our findings reveal a novel specific interaction between thymocytesand a specialized subset of TE cells.
Specific epitope‐induced conversion of CD8+ memory cells into effector cytotoxic T lymphocytes in vitro: presentation of peptide antigen by CD8+ T cells
Authors: Kos Ferdynand J. , Müllbacher Arno 
Published: March 2007

AbstractThe requirements for the conversion of CD8+ memory T cells into effector class I major histocompatibility complex (MHC) Kd−restricted cytotoxic T (Tc) cells in vitro have been studied. Purified CD8+splenocytes from influenza A/WSN‐primed BALB/c (H‐2d) mice stimulated with a synthetic nucleoprotein peptide 147–158 R156− (NPP) alone generated Tc cells specific for influenza virus‐infected target cells. No additional requirements for accessory cells or their lymphokine products were necessary indicating that peptide antigen (Ag) in association with Kd was presented on CD8+ T cells. The evidence for presentation of NPP by CD8+ T cells was supported by the use of CD8+ memory T cells from semiallogeneic bone marrow radiation chimeras of P1 → F1 type (H2b→ [H‐2d x H‐2b]F1). Memory CD8+ splenocytes from A/WSN‐immune chimeras did not develop into secondary effector Tc cells as a result of a 4‐day culture with NPP alone, however, were able to do so if NPP was presented by Kd−bearing Ag‐presenting cells. In addition, these results exclude the possibility of direct recognition of free NPP molecules by the specificT cell receptor of CD8+ memory T cells. CD8+ memory splenocytes (H‐2b) from chimeras were also able to develop into functionally active Tc cells as a result of presentation of Db−restricted synthetic peptide (NP 366–374) with a sequence derived from influenza virus nucleoprotein with high affinity for Db MHC class I molecules. Blockade of endogenously produced interleukin 2 (IL‐2) activity by anti‐IL‐2 or anti‐IL‐2 receptor monoclonal antibody in the culture of CD8+ memory T cells during a 4‐day NPP stimulation completely abolished Tc cell generation, indicating that the utilization of this lymphokine is absolutely required for the secondary Tc cell development. These findings demonstrate that CD8+ memory T cells per se are able to recognize the restimulating epitope as a result of its presentation by CD8+ T cells and develop into cytolytically active and highly specific Tc cells with no requirements for other cellular helper components or their lymphokine products.
The fate of the three subunits of major histocompatibility complex class I molecules
Authors: Neefjes Jacques J. , Smit Linda , Gehrmann Matthias , Ploegh Hidde L. 
Published: March 2007

AbstractAt the surface of the murine T lymphoma cell line RMA‐S, the expression of “empty” class I molecules can be dramatically enhanced by culture at 26°C. These class I molecules are unstable following transfer to 37°C unless they are loaded with exogenously added peptides. Class I heterodimers that have failed to bind peptide (“empty” class I molecules) dissociate and the class I heavychains are degraded. Internalization, if it precedes breakdown, would be the rate‐limiting step.Radioiodinated peptides (VSV NP8‐mer or Sendai NP9‐mer) dissociate from the class I molecules in the absence of exogenous peptide or β2 microglobulin and appear in the medium. Release of the iodinated peptides does notresult in a reduction in the quantity of stable assembled class I molecules. This paradox may be explained by a more rapid off‐rate for radioiodinated peptides, when compared with their unlabeled counterparts, which constitute about 99% of the total in our radiolabeled preparations. In the medium the peptide is rapidly modified by serum‐ and cell‐derived proteases. The short half‐life of empty class I molecules and offree ligand would effectively preclude sensitization of innocent bystanders for lysis by cytotoxic T lymphocytes.
Aberrant interleukin (IL)‐4 and IL‐5 production in vitro by CD4+ helper T cells from atopic subjects
Authors: Parronchi Paola , de Carli Marco , Manetti Roberto , Simonelli Cecilia , Piccinni Marie‐Pierre , Macchia Donatella , Maggi Enrico , Prete Gianfranco Del , Ricci Mario , Romagnani Sergio 
Published: March 2007

AbstractThe cytokine secretion profiles of T cell lines (TCL) specific for purified proteinderivative (PPD) or streptokinase (SK), contemporarily derived from nine atopic and nine nonatopic individuals, were compared. Upon stimulation with phorbol myristate acetate(PMA) plus anti‐CD3 monoclonal antibody (mAb), all TCL from both atopics and nonatopics produced interleukin (IL)‐2 and interferon (IFN)‐γ. The mean IL‐2 production by PPD‐ or SK‐specific TCL from both atopics andnonatopics was similar, whereas the mean IFN‐γ production by TCL derived from atopics was significantly lower. In addition, both PPD‐ and SK‐specific TCL from atopics produced detectable amounts of IL‐4 and IL‐5, whereasthe corresponding TCL derived from nonatopics did not.A total number of 107 and 99 PPD‐specific CD4+ T cell clones (TCC)were then derived from TCL of 4 atopic and 4 nonatopic donors and assessed for their profile of cytokine production in response to stimulation with either PMA plus anti‐CD3 mAb or the specific antigen. Under both these experimental conditions, virtually all PPD‐specific TCC from both atopic and nonatopic individuals produced IL‐2 and IFN‐γ. In contrast, the great majority of PPD‐specific TCCderived from nonatopic individuals did not produce IL‐4 and IL‐5, whereashigh proportions of PPD‐specific TCC derived from atopic donors displayed the ability to produce noticeable amounts of IL‐4 and IL‐5 besides IL‐2 and IFN‐γ.These data indicate that CD4+ T cells from atopic individuals are able toproduce IL‐4 and IL‐5 in response to bacterial antigens, such as PPDand SK, that usually evoke responses with a restricted type‐1 T helper (Th1)‐like cytokine profile in nonatopic individuals. Aberrant IL‐4 production by Th cells may represent one of the immune alterations responsible for enhanced IgE antibody production in atopic people.
FcγRIII activation is different in CD16+ cytotoxic T lymphocytes and natural killer cells
Authors: Uciechowski Peter , Gessner J. Engelbert , Schindler Ralf , Schmidt Reinhold E. 
Published: March 2007

AbstractThe transmembrane protein CD16 (FcγRIII) is detected on activated macrophages, natural killer (NK) cells and a small subset of T lymphocytes. From CD3− CD56+ CD16+bright NK cells and CD3+ CD56+ CD16+dim non‐major histocompatibility complex (MHC)‐restricted cytotoxic T lymphocyte (CTL) clones were generated reflecting the stable, but different, CD16 expression of the respective peripheral blood subpopulations. To compare the role of CD16 on NK cells and non‐MHC‐restricted CTL, FcγRIII activation and its mechanisms were investigated using monoclonal antibodies (mAb). Cross‐linking of CD16 induced Ca2+ influx in CD16+bright NK clones. In contrast, there was no Ca2+ mobilization after CD16 activation in CD16+dim CTL, which revealed a good response to cross‐linking of CD3 antigen. Pretreatment with CD16 mAb alone or cross‐linked CD16 mAb did not block the CD3 response of CD16+dim CTL. Again, CD16 cross‐linking induced more interferon‐γ transcription in NK cell clones than in non‐MHC‐restricted CTL clones. Also a higher tumor necrosis factor‐α production of NK clones after CD16 cross‐linking compared to CD16+dim CTL could be observed. These data suggest that after CD16 activationCD16+dim CTL and CD16+bright NK cells use different second messengers. In addition, signal transduction via CD3 and CD16 appears to function independently in CD16+dim non‐MHC‐restricted CTL.
Inhibition of abnormal T cell development and autoimmunity in gld mice by transgenic T cell receptor β chain
Authors: Yui Katsuyuki , Bhandoola Avinash , Komori Shinji , Katsumata Makoto , Greene Mark I. , Radic Marko Z. 
Published: March 2007

AbstractMice homozygous for the gld (generalized lymphoproliferative disease) mutation develop systemic autoimmune disease and severe lymphadenopathy due to an age‐related accumulation in the peripheral lymphoid organs of polyclonal T cells bearing a unique phenotype (CD4−CD8−TCR αβ+B220+). These T cells overex‐press T cell receptor (TcR) αβ chain RNA, proto‐oncogenes c‐myb and fyn, and proliferate poorly in response to TcR‐mediated stimulation. The origin of these T cells is poorly understood. To study the influence of a functionally rearranged TcR β chain on the T cell developmental abnormality of the gld mutation and autoimmunity, we have backcrossed TcR Vβ8.1‐transgenic mice to C3H‐gld/gld to homozygosity (transgenic gld mice). In transgenic gld mice, lymphadenopathy was markedly inhibited and the accumulation of CD4−CD8− T cells did not occur, although the remaining T cells overexpressed c‐myb and proliferated poorly in response to TcR occupancy. These features indicate that the pattern of proto‐oncogene expression and abnormal function persist in phenotypically normal T cells in transgenic gld mice, and that these characteristics can be dissociated from the accumulation of CD4−CD8− T cells. The hypergammaglobulinemia and anti‐double‐stranded DNA (anti‐dsDNA) antibody production was partially improved in transgenic gld mice, supporting the critical role of T cells in abnormal B cell activation described in autoimmunity‐prone mice. To investigate further the mechanisms underlying the inhibition of CD4−CD8− T cell accumulation in transgenic gld mice, the fetal ontogeny of T cells in transgenic mice was compared with that of non‐transgenic mice. In transgenic thymus, development of TcR αβ+ cells was accelerated as detected by earlier expression of CD4, CD8 and TcR in fetal thymus. In contrast, the number of TcR γδ+ cells was reduced. We suggest that altered T cell development in transgenic mice directly or indirectly inhibits the accumulation of abnormal T cells in gld mice.
Characterization and measurement of CD5+ B cells in normal and Trypanosoma congolense‐infected cattle
Authors: Naessens Jan , Williams Diana J. L. 
Published: March 2007

AbstractCD5+ B cells in cattle are present in peripheral blood and spleen, but not in lymph nodes, tonsils or Peyer's patches. Compared to classical B cells, they express similar levels of B cell surface markers, but have higher levels of surface IgM. We failed to find evidence for IgD on bovine B lymphocytes. The CD5+ B cells expressed CD11b (Mac‐1). Another small subpopulation of B cells carried CD11b but not CD5. In cattle infected with Trypanosoma congolense, a dramatic increase in the percentage of CD5+ B cells in blood and spleen was observed. This increase occurred 7‐10 days after parasites were first detected in the blood and correlated with the increase in serum IgM and the increase in the absolute number of B cells that is typical to trypanosome‐infected animals. The increase in B cells was found to be due mainly to the expansion of the CD5+ B cell subpopulation. The cause of the amplification of the CD5+ B cells and their possible involvement in the production of autoantibodies and non‐parasite‐specific antibodies which have been described in trypanosome‐infected animals are discussed.
Human peripheral blood leukocytes transplanted on CB17 scid‐scid mice are transferred to their offspring
Authors: Ladel Christoph H. , Püschner Hubert , Kaufmann Stefan H. E. , Bamberger Uwe 
Published: March 2007

AbstractSevere combined immunodeficient (scid) mice are deficient in functional T cells and B cells. Hence, scid mice reconstituted with human peripheral blood leukocytes (scid‐huPBL) provide an excellent model for analysis of the human immune response under in vivo conditions. We have investigated this model further by analyzing human immune responses in the progeny of scid‐huPBL (termed scid‐humo). We find markedly elevated levels of human immunoglobulins (Ig) in the serum of scid‐humo for more than 12 weeks indicating materno‐fetal transfer of human B lymphocytes. Consistent with this finding we obtained evidence for the existence of human lymphocytes in scid‐humo. Murine Ig levels in scid‐humo were also elevated and surface Ig‐expressing cells (probably B cells) were demonstrable. In this respect scid‐humo resembled “leaky” scid. In contrast to “leaky” scid, scid‐humo accepted transfer of human blood leukocytes. Not only leukocytes from autologous but also those from heterologous donors were accepted. Human Ig levels in scid‐humo increased more rapidly as compared to normal scid mice. Thus, despite these increased B cell activities in scid‐humo, transferred human leukocytes were not affected indicating that materno‐fetal transfer of human cells had caused tolerization or conditioning. This is in contrast to scid mice in which elevated Ig levels correlate with increased failure rates of reconstitution with human blood leukocytes. We propose that scid‐humo provide an improved model for studying the human immune responses in an in vivo setting.
Restoration of the LFA‐3 adhesion pathway in Burkitt's lymphoma cells using an LFA‐3 recombinant vaccinia virus: consequences for T cell recognition
Authors: Griffin Heather , Rowe Martin , Murray Ruth , Brooks Jill , Rickinson Alan 
Published: March 2007

AbstractConjugate formation between cytotoxic T lymphocytes (CTL) and target B cells, as observed in vitro, is mediated by interactions between adhesion molecules on the two cell surfaces rather than involving immune recognition through the T cell receptor. It is still not clear to what extent such adhesive contacts facilitate the process of immune recognition and target cell lysis. However, work on the Epstein‐Barr virus (EBV)‐associated malignancy Burkitt's lymphoma (BL) has suggested that down‐regulation of one particular adhesion molecule, the lymphocyte function‐associated antigen LFA‐3, on the tumor cell surface is a key factor in allowing these target cells to escape EBV‐speficic T cell surveillance. To examine this directly, we used a cDNA for the full‐length transmembrane form of LFA‐3 to construct a recombinant vaccinia virus (Vacc‐LFA 3), which is capable of restoring surface LFA‐3 in adhesion molecule‐negative BL cell lines to levels as high as seen in EBV‐transformed lymphoblastoid cell lines (LCL); biochemical studies confirmed expression of the authentic N‐glycosylated protein. The recombinant vaccinia‐encoded LFA‐3 was functional as an adhesion molecule since BL cells acutely infected with Vacc‐LFA‐3 then acquired the ability to form conjugates with activated T cells in vitro. However, there was no clear dependence upon LFA‐3 when such BL cell lines were tested as targets for cytotoxic T lymphocytes (CTL). Firstly, LFA‐3− BL cells could be killed by allospecific CTL recognizing HLA class I alloantigens, in some cases as efficiently as the corresponding LCL. In other cases where lysis was slightly below that of the LCL, Vacc‐LFA‐3 infection of the BL cells increased lysis up to, but never beyond, LCL values. Secondly, we studied the sensitivity of BL to EBV‐specific HLA class I‐restricted CTL using a BL target line which was LFA‐3− but which expressed the same spectrum of EBV target proteins as an LCL. This line was not recognized by appropriately HLA‐matched effectors, even after restoration of LFA‐3 expression. We conclude that the LFA‐3 status of BL cells influences their conjugate forming ability in in vitro assays but not necessarily their sensitivity to immune T cell‐mediated cytolysis.
Selection of murine T cell receptor αβ and γδ cells in organ cultures established from 14‐day embryos
Authors: Fisher Amanda G. , Waltzinger Caroline , Ceredig Rhodri 
Published: March 2007

AbstractThe expression of minor lymphocyte stimulatory locus (Mls) determinants in combination with murine major histocompatibility complex (MHC) class II molecules, leads to the destruction of lymphocytes bearing specific V region‐encoded T cell receptor (TcR) products. A much studied example is the elimination of Vβ6+ cells in IE+/Mls‐1a mice, in which deletion can be detected 7‐10 days after birth but is not fully operational earlier in embryonic life. Here we investigate this transitional period in development and show that selective deletion of Vβ6 occurs in vitro, approximatively 1 week after organ cultures are established from 14 day embryos. These unmanipulated organ cultures receive no additional cell immigrants after day 14, suggesting that the cellular elements mediating negative selection (or their direct precursors), are already resident in the fetal thymus by day 14 of gestation. Hence, the developmental timing of the outset of rigorous negative selection of Vβ6 is not dictated by the postnatal entry of deleting elements into the thymus, but perhaps by the maturation of the pre‐existing environment. Using a parallel organ‐culture approach we have looked at the development of Vδ4 and Vγ3, TcR γδ+ cells in a variety of mouse strains. These receptors have recently been reported to be subject of MHC and non‐MHC linked selection, respectively. We find that after an initial period of expansion, the number of Vγ3‐expressing cells dramatically declines. However, this selective loss of Vγ3 cells is not contingent on the C57BL/6 mouse strain (in contrast to a previous report). These findings are discussed in the context of current models of ontogeny and repertoire selection.
Molecular analysis of the VxIII‐Jx junctional diversity of polyclonal rheumatoid factors during rheumatoid arthritis frequently reveals N addition
Authors: Martin Thierry , Blaison Gilles , Levallois Honey , Pasquali Jean Louis 
Published: March 2007

AbstractMuch interest was stirred in recent years by the evidence that rheumatoid factors (RF) variable regions are encoded by a restricted set of V genes, with little or no somatic mutations, that are often overexpressed in the fetal repertoire. This is reminiscent of what has been observed for natural autoantibodies. However, these data come from studies of monoclonal RF (mRF) isolated from patients with lymphoproliferative disorders who usually do not present autoimmune symptoms. The molecular characterization of RF during autoimmune diseases such as rheumatoid arthritis (RA) has been hampered for some time because of their polyclonality; recently using the polymerase chain reaction method, we have demonstrated that RFχ variable regions from a patient with RA were encoded by VχIII genes known to code for mRF but that these genes had undergone somatic mutations with a pattern suggesting an antigen‐driven maturation. Because an important role of the light chain third complementarity‐determining region (CDR3) in anti‐IgG reactivity and idiotype expression has already been suspected for RF, we now report the molecular characterization of the junction regions of these rearranged Vχ genes. Surprisingly, our data show that in 55% of the cases there is addition of a proline and/or glycine amino acid residue at the recombination site between Vχ and Jχ. The sequence analysis of our patients' germ‐line Vg and Jχ4 gene segments and their flanking regions demonstrates that the additional codons are not readily explicable by recombination between germ‐line sequences and probably result from an N addition process. Since we could not find such an additional codon in 15 previously published mRF χ chains we suggest that “pathogenic” RF during RA and mRF derive from different, although overlapping, B cell subsets. Moreover, since additional codons at the recombination site of Vχ and Jχ seem exceptional in expressed human χ chains and because the resulting amino acid residue is a proline in most cases, we think that RFχ chain CDR3 is under a very strong selective pressure during RA.