bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pre‐B cell differentiation in the bone marrow: A proliferative pathway parallels the post‐mitotic maturation of early B cells
Authors: Deslauriers‐Boisvert Nöella , Mercier Ginette , Lafleur Louis 
Published: February 2007

AbstractConsiderable heterogeneity was found in bone marrow B cell progenitors as functionally defined, size‐separated populations were analyzed for their density of membrane IgM receptors, their adherence potential to nylon wool fibers and their susceptibility to lipopolysaccharide‐induced differentiation to IgM secretion. The investigation of their cycling status with tritiated thymidine further permitted definition of resting and actively proliferating populations. Heterogeneity was found in the fraction of resting small cells as expected for early B cells progressing through postmitotic maturation. However, the data suggest that part of the pre‐B cell progeny can also mature during a proliferative phase.
Human lymphocyte proliferation II. Formation of activated (G1) cells
Authors: Bettens Florence , Kristensen Flemming , Walker Christoph , de Weck Alain L. 
Published: February 2007

AbstractThe kinetics of phytohemagglutinin (PHA)‐stimulated human peripheral blood lymphocytes in the early phases (G0, G1a, G1b) of the first cell cycle have been analyzed in vitro by cytofluorometry and [3H] thymidine incorporation. Cells were detected in the G1a G1b and S phases 12‐14, 20‐22 and 24‐26 h after stimulation, respectively. The total number of PHA‐induced G1 cells reached a plateau after 32 h of incubation, upon which a second increase followed, 10 h later. The latter increase was considered to be a result of cells initiating their second cell cycle, since it could be abolished by hydroxyurea.By examination of supernatants, interleukin 2 (IL 2) activities could be recovered 6 10 h after PHA stimulation. In contrast, the monokine IL 1 was already detected after 2 h. Both interleukins were present in the culture medium before the major G1a, cell formation took place. The titer of free IL 2 increased to a maximum after 18‐22 h, whereafter a decline was observed. This decline was less pronounced if cultures were treated with hydroxyurea. Finally, among individual donors, the total number of lymphocytes entering the G1 phase and the time at which the G1a‐G1b transition took place varied. Lower numbers of G1 cells and delayed G1a‐G1b transition coincided with lower IL 2 titers and delayed occurrence of maximal titers in the supernatants.
Clonal differences in response to T cell replacing factor (TRF) for IgM secretion and TRF receptors in a human B lymphoblast cell line
Authors: Saiki Osamu , Ralph Peter 
Published: February 2007

AbstractA number of human B lymphoblast cell lines were tested to find a suitable model for induction of immunoglobulin‐secreting cells (ISC) by T cell replacing factor (TRF). Partially purified TRF was size fractionated from the conditioned medium of irradiated (1000 rds) human spleen cells stimulated with pokeweed mitogen. IgM line SKW 6 showed high levels of TRF‐stimulated immunoglobulin secretion and was chosen for cloning experiments. Clone 11 had a very low level of ISC with or without TRF (less than 0.1% ISC). Clone 4 had low background numbers of ISC (0.2%) and showed the highest degree of stimulation by TRF (to 6% IFC). High secreting clone 8‐2 (6%) was not stimulated significantly by TRF. These clones had the same HLA‐DR antigens, and their levels of ISC and sensitivity to TRF were relatively stable over three months of observation. The TRF preparation also had strong helper activity for normal peripheral blood B cell differentiation. TRF activity for both normal B cells and clone 4 cell line was absorbed by all 3 clones, but not by a pre‐B line. This suggests that the effector molecules for normal B cell and cell line differentiation were the same. The three typical clones corresponding to nonresponding, responding, and high rate‐secreting B cells provide basic models for analyzing B cell receptors for TRF and the biochemical effects of TRF during B cell differ entiation.
Enhanced expression of human Ia antigens by chronic lymphocytic leukemia cells following treatment with 12‐O‐tetradecanoylphorbol‐13‐acetate
Authors: Guy Keith , Van Heyningen Veronica , Dewar Edna , Steel C. Michael 
Published: February 2007

AbstractUsing a panel of monoclonal antibodies which detect framework determinants of human‐Ia à and β polypeptides and the DC‐specific monoclonal antibody Genox 353, the in vitro effects of 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA) on the expression of Ia antigens by cells from chronic lymphocytic leukemia (CLL) patients have been studied. In all subjects studied a great increase in expression of framework Ia determinants was found following culture of CLL cells for 90 h with TPA at 10−7 g/ml. TPA treatment of CLL cells also induced increased expression of Genox 353+ antigens, in some cases where Genox 353 binding was either negligible or not detectable in cells cultured in the absence of TPA.
Immunoglobulin isotype in the murine response to polysaccharide antigens
Authors: Moreno Carlos , Esdaile Jane 
Published: February 2007

AbstractMurine antisera specific for the α (1→3) and α (1→6)‐linked glucosyl determinants of dextran, as well as for meningococcal polysaccharide group C, have been examined for the distribution of their immunoglobulin classes and subclasses. Whereas the thymus‐independent anti‐α (1→3) dextran response in BALB/c mice was found to be IgM > IgG3 > IgA, thus corresponding to previously published work, neither the α (1→6) response in its thymus‐dependent or‐independent form, nor the response to purified meningococcal polysaccharide, corresponded to this pattern. No preference for any of the IgG subclasses appeared for these antigens when given as thymus‐independent carbohydrates. On the other hand, thymus‐dependent forms of α (1→6) dextran showed an IgG1 > IgG3 > IgG2 pattern.
Effect of cyclosporin A on the induction and activation of B memory cells by thymus‐independent antigens in mice
Authors: Shidani Babak , Colle Jean‐Hervé , Motta Iris , Truffa‐Bachi Paulo 
Published: February 2007

AbstractThe effect of cyclosporin A on the induction and activation of B memory cells by thymus‐independent (TI) antigens was investigated. Studies were carried out in C57BL/6 mice, a strain in which TI.1 trinitrophenyl‐lipopolysaccharide (TNP‐LPS) and TI.2 dinitrophenyl‐(DNP)‐Ficoll antigens can elicit a secondary response. Evidence is presented that cyclosporin A does not adversely affect the primary or secondary response to TNP‐LPS. In contrast, this fungal metabolite prevents the triggering of virgin B lymphocytes and TNP‐LPS‐induced memory cells by DNP‐Ficoll. Cyclosporin A does not interfere with the generation of hapten‐specific B memory cells by TNP‐LPS or DNP‐Ficoll. These findings are discussed in terms of B cell lineages leading to antibody‐forming cell precursors and memory cells.
Characterization of a subpopulation in neonatal thymus which suppresses the graft‐vs.‐host reaction
Authors: Van Bekkum Dirk W. , Knaan‐Shanzer Shoshan 
Published: February 2007

AbstractThymus cells from neonatal and infant mice were found to have a high capacity to prevent mortality from acute graft‐vs.‐host disease as compared with spleen cells from stable radiation chimeras. This suppressive capacity of thymocytes decreases with age after birth as was demonstrated by semi‐quantitative cell titrations. This suppressor activity is restricted to syngeneity of the graft‐vs.‐host disease‐including cells. The thymic suppressor cells are Thy‐1+ and Lyt‐1+ and IgG− and IgM−. They do not agglutinate with peanut agglutinin and have a high electrophoretic mobility. In vitro irradiation experiments showed that the suppressor cells are radiation sensitive. These results are compared with the available information on cells suppressing delayed‐type hypersensitivity reactions and those suppressing B cell responses.
IgG subclass distributions in anti‐hapten and anti‐polysaccharide antibodies induced by haptenated polysaccharides
Authors: Sarvas Heikki O. , Aaltonen Leena M. , Péterfy Ferenc , Seppälä Ilkka J. T. , Mäkelä Olli 
Published: February 2007

AbstractMice were immunized with hapten [NIP, (4‐hydroxy‐5‐iodo‐3‐nitrophenyl)acetyl or TNP (2,4,6‐trinitrophenyl)] conjugates of Ficoll or pneumococcal polysaccharide type 14 (S14), and they were bled on days 10 or 14. Anti‐hapten and anti‐polysaccharide antibodies were determined from the sera or from fractions (IgM + IgA), IgG1, IgG2a, IgG3 or IgG2h separated by a gradual acid elution from protein A. Approximately one‐half of both anti‐hapten and anti‐polysaccharide antibodies was found in the IgM + IgA fraction. The subclass distribution of the IgG antibodies was dependent on the antigenic determinants. Polysaccharide antibodies were mostly in the IgG3 fraction (36–62%) and in the IgG1 fraction (18–36%). Hapten IgG antibodies were mostly in the IgG1 fraction (38–74%); each of the other three subclasses contributed the average of 13%. These results provide the first evidence that antibodies to different determinants of one antigen have grossly different isotype distributions.
Effect of anti‐γ3 antibodies on immunoglobulin isotype expression in lipopolysaccharide‐stimulated cultures of mouse spleen cells
Authors: Webb Carol F. , Gathings William E. , Cooper Max D. 
Published: February 2007

AbstractTo test the hypothesis that γ3 is the pivotal isotype for sequential heavy chain switching from μ to each of the γ isotypes, we have compared the effects of anti‐γ3 and anti‐μ antibodies on the expression of immunoglobulin isotypes in lipopolysaccharide (LPS)‐stimulated cultures of mouse spleen cells. IgM‐, IgG1‐, IgG2b‐ and IgG2a‐containing plasma cells were enumerated by immunofluorescence and secreted immunoglobulins were measured by radioimmunoassay. Although anti‐γ3 and anti‐μ, were equally effective in inhibiting the LPS‐induced differentiation of IgG3 plasma cells, anti‐γ3 had no effect on the differentiation of IgM, IgG1, IgG2b, or IgG2a plasma cells. These results support a direct mechanism of heavy chain immunoglobulin switching.
A functional homologue of mammalian secretory component exists in chickens
Authors: Peppard Jane V. , Rose M. Elaine , Hesketh Patricia 
Published: February 2007

AbstractThe existence of a molecule in chickens homologous to the secretory component of mammals has long been in dispute. An intravenous injection of [14C]fucose was given to chickens as a marker for newly synthesized glycoproteins and then unlabeled human IgA was injected intravenously half an hour later. It was shown that the human IgA subsequently appeared in the bile of the chickens combined with a [14C]fucose‐labeled molecule; the chicken IgA in these bile samples was similarly labeled. Radiolabeled human secretory IgA was not transported in large amounts across the chicken liver in vivo and neither was purified chicken bile IgA. These results indicate that a molecule exists in chickens which behaves in a manner analogous to mammalian secretory component.
The T3 complex on human thymus‐derived lymphocytes contains two different subunits of 20 kDa
Authors: Borst Jannie , Prendiville Mary Ann , Terhorst Cox 
Published: February 2007

AbstractThe human cell surface antigen T3 is involved in several T lymphocyte specific functions, as determined by the effect of monoclonal antibodies (OKT3, anti‐Leu‐4, UCHT1) directed at this molecular structure. The main target antigen of these monoclonal antibodies is a glycoprotein of 20 kDa. It is associated with four, less predominant, structurally distinct glycoproteins of 25‐28 kDa, 37 kDa and 44 kDa. Of these molecules only the 20‐kDa T3 antigen could be labeled with the hydrophobic reagent 5‐iodonaphthyl‐1‐azide (INA). Here we present evidence that the main 20‐kDa T3 antigen is comprised of, in fact, two structurally different molecules. One of these is a glycoprotein with a protein backbone of 14 kDa, the other is an unglycosylated protein of 20 kDa. This unglycosylated protein is labeled specifically with INA. Additional evidence for the existence of two different 20‐kDa T3 antigens is provided by studies using the enzymes endo‐β‐N‐acetylglucosaminidase H and endo‐β‐N‐acetylglucosaminidase F and the drug tunicamycin. We hypothesize that the specific susceptibility to labeling with INA of the unglycosylated 20‐kDa T3 form reflects a positioning in the lipid bilayer different from that of the glycosylated 20‐kDa T3 form.
Immunoglobulin expression in diploid and polyploid interspecies hybrids of Xenopus: evidence for allelic exclusion
Authors: Pasquier Louis Du , Hsu Ellen 
Published: February 2007

AbstractThe expression of species‐specific surface IgM was studied in various Xenopus species hybrids. Whether the hybrids are diploid or polyploid, a lymphocyte does not produce all of the immunoglobulins (Ig) encloded by the Ig genes present in its genome. This suggests that the selection pressure to make a lymphocyte synthesize only one antibody is high and that allelic exclusion already existed in the ancestors of amphibians which appeared 300 million years ago.The apparent lack of cells producing multiple Ig in polyploid hybrids having more than one pair of functional Ig genes suggests that if a stochastic model for allelic exclusion is correct, the frequency of multiple successful rearrangements has to be very low, resulting in a huge waste of lymphocyte precursors. Given the particularity of frog development it is argued that this is not likely to be the case.
Ontogenic restriction of colonization of the bursa of Fabricius
Authors: Houssaint Elisabeth , Toraño Alfredo , Ivanyi Juvaj 
Published: February 2007

AbstractThe capacity of hemopoietic precursor cells (HPC) to home to embryonic bursal and thymic grafts was investigated in embryonic and newly hatched chickens. Whereas thymic grafts developed normal histogenesis in both types of recipients, the bursal rudiment was colonized and developed in embryonic, but not in newly hatched hosts. In the latter, noncolonized bursal grafts developed neither lymphoid follicles nor granulopoiesis in the mesenchyme. These results are interpreted in terms of ontogenic “maturation” of the HPC which lose their homing potential towards the bursa while they preserve their thymic seeding capacity. This hypothesis is consistent with previously reported data which indicated cyclic continuous recruitment of the thymic lymphoid population, but restricted bursal colonization to a relatively brief period of embryonic life.
Desensitization of macrophages to stimuli which induce secretion of superoxide anion. Down‐regulation of receptors for phorbol myristate acetate
Authors: Berton Giorgio , Gordon Siamon 
Published: February 2007

AbstractThe ability of cultivated mouse peritoneal macrophages (MΦ) to release superoxide anion (O2−) after repeated stimulation by phorbol myristate acetate (PMA) or serumtreated zymosan (STZ) has been studied. After a maximal first stimulus bacillus Calmette‐Guérin (BCG)‐activated MΦ released high levels of O2−, 2‐fold more than thioglycollate‐elicited MΦ and the response ceased within 4 h. Both populations either responded again to a second challenge or displayed a refractory state which varied in duration and selectivity. Desensitization by STZ pretreatment was transient and selective whereas PMA could render MΦ refractory for 3 days to PMA alone or to both agents, depending on the amount of PMA used and the conditions of stimulation. PMA induced a selective loss of specific saturable receptors for [3H]phorbol dibutyrate, a closely related agent, and receptor activity recovered with the ability to release O2−. Loss of receptors did not account for concomitant loss of the response to STZ after nonselective deactivation. Such MΦ were fully viable and able to endocytose various soluble and particulate ligands vigorously, but without stimulation of the hexose monophosphate shunt or release of O2−.Our studies indicate that MΦ activities can be profoundly altered by prior stimulation, that specific receptors play a role in ligand‐induced desensitization and that agents such as PMA can selectively eliminate the cells′ ability to generate a second respiratory burst.
Mapping epitopes on the insulin molecule using monoclonal antibodies
Authors: Schroer Joyce A. , Bender Timothy , Feldmann Richard J. , Kim K. Jin 
Published: February 2007

AbstractA panel of 18 monoclonal antibodies (mAb)Δ to insulin have been prepared and used to begin to map antigenic determinants on the insulin molecule. All 18 mAb were of the IgG class, with 14 IgG1, 2 IgG2a and 2 IgG2b. The affinities of these mAb for their immunizing insulin ranged from 1 × 106 to 3 × 108 1/M. The epitope recognized by three of the mAb, 1, 7 and 16 involves the three residues of the A chain, A 8‐10, the so called A chain‐loop determinant. This A chain loop is one of the most evolutionarily diverse regions of insulins from different species. Another mAb, 10, has been hypothesized to recognize a nearby epitope composed of the A chain residues, A4 and A8 and a B chain residue, B29, that are adjacent on the surface of the insulin molecule. Four of the mAb bind to synthetic B chain. The epitopes recognized by these 4 mAb and the last 10 mAb are unknown but the mAb are grouped according to their ability to bind to different species of insulin or proinsulin. The results of an 18 × 18 matrix analysis of pairs of mAb binding simultaneously to insulin indicate that, despite the finding that some mAb see similar antigenic sites on the insulin molecule, each of the mAb recognizes a unique site on the insulin molecule. Finally, a lower estimate of the number of possible antibodies made to insulin has been calculated to be ≧ 115, a number only 10‐fold lower than the lower limit of antibodies made to dinitrophenyl (DNP) or (4‐hydroxy‐5‐iodo‐3‐nitrophenyl)acetyl (NIP), following hapten protein immunization.
Differential requirements for activation and growth of unprimed cytotoxic and helper T lymphocytes
Authors: Gullberg Martin , Pobor Grgur , Bandeira Antonio , Larsson Eva‐Lotta , Coutinho Antonio 
Published: February 2007

AbstractThe requirements for activation and growth of T lymphocytes capable of mediating either cytolytic activity or help to B lymphocytes were studied in unprimed splenic T cell populations. The selectivity of expression of Lyt‐2 antigens, the reactivity to soluble concanavalin A (Con A), to partially purified interleukin 2 (IL2, T cell growth factor[s]) and to lectin‐pulsed macrophages (MΦ) were used in this analysis. Lectin‐dependent cytotoxicity assays and a novel method that allows for the detection of all effector helper cells, regardless of their clonal specificities, were used for the functional identification of the responding T cells.The results show a marked contrast between cytolytic and helper T cells in their growth and activation requirements. Thus, while Lyt‐2+ cytotoxic T lymphocyte precursors grow exponentially in IL2 after a short pulse with soluble Con A in the absence of accessory cells, Lyt‐2− helper cell precursors completely fail to proliferate under the same conditions and require the continuous presence of lectin‐pulsed MΦ for significant growth. Furthermore, addition of IL2 to MΦ‐stimulated cultures of Lyt‐2− cells has no effect. T cells which produce IL2 have the same growth characteristics as helper cells. In both cases, effector helper functions could be expanded more than 10‐fold on a per cell basis by a 5‐day‐culture period under those growth supporting conditions. The development of effector helper functions, however, was strongly inhibited by the presence of Lyt‐2+ T cells.
The immune response against anti‐idiotope antibodies II. The induction of antibodies bearing the target idiotope (Ab3β) depends on the frequency of the corresponding B cells
Authors: Tesch Hans , Takemori Toshitada , Rajewsky Klaus 
Published: February 2007

AbstractIn the present study we use two monoclonal anti‐idiotope antibodies (Ac38 and Ac146; Ab1) against the germ line‐encoded, λ1 chain‐bearing and (4‐hydroxy‐3‐nitrophenyl)acetyl (NP)‐binding antibody Bl‐8 (Ab1) for the induction of complementary antibodies (Ab3) and ask the question to what extent antibodies bearing Bl‐8‐like idiotopes (Ab3β) are represented in the Ab3 population. In this experimental system, Ab3β is distinguished from the remaining Ab3 population (Ab3α) by three properties which Ab3β may share with Bl‐8: (a) the binding of NP, (b) the binding to Ac146 (if induced by Ac38) or the binding to Ac38 (if induced by 146) and (c) that they carry λ1 chains.Antibodies with all three properties are induced in low amounts by both anti‐idiotopes. Also, Ac146 induces only Ab3α (bearing x chains and not binding NP and Ac38). In contrast, Ac38 triggers almost exclusively a λ1 chain‐bearing response, i.e. Ab3β. The response has an unusually large size, reaches its maximum after a week and is long‐lasting. An analysis at the level of lipopolysaccharide‐reactive precursor B cells demonstrates that, in this case, cells expressing Ab3β occur at exceedingly high frequency (≈ 10−3) and are at least 10 times more frequent than cells expressing Ab3α. The high frequency of Ab3β‐expressing cells correlates with the contribution of several VH, D and J genes to the expression of this particular idiotope. In the case of the Ac146 anti‐idiotope antibody, the response is dominated by Ab3α. Ab3β represents less than 10% of the total response, reaches maximal levels 2 weeks after immunization and declines rapidly. This correlates with a low frequency of precursor B cells expressing Ab3β (≈ 10−5) and a restriction of the corresponding idiotope to rare VH‐D combinations, caused presumably by a stringent contribution of the H chain to this idiotope which covers the NP‐binding site.Our data suggest that anti‐idiotypic antibodies (Ab2) against Ab1 will preferentially induce antibodies idiotypically related to Ab1 if the corresponding idiotopes are expressed in high frequency in the B cell compartment. This is expected in cases where Ab2 recognizes an idiotope that can be formed by many germ line‐encoded VH‐D‐VL‐combinations.
Natural cytotoxicity in the mouse embryo: characterization of yolk sac‐associated natural cytotoxic cells and their activity
Authors: Dahl Carol A. 
Published: February 2007

AbstractThe natural cytotoxic activity of yolk sac (YS) cells from 10‐day mouse embryos against YAC‐1 tumor targets was characterized for its sensitivity to modulation by a variety of factors. Experiments demonstrated the observed levels of tumor cell lysis to be unaffected by the strain of origin of the YS cells, trypsin pretreatment of the YS population, as well as a prior stimulation by environmental pathogens. Both the YS natural cytotoxic (YSNC) activity and the adult natural killer (NK) cell activity were found to be depressed when assayed in the presence of amniotic fluid. YS cells were tested for antibody‐dependent cell‐mediated cytotoxic activity, but were not found to generate significant levels of lysis.Experiments presented here demonstrate the YSNC activity to be dependent upon only a subpopulation of YS cells. The YSNC activity was found to be associated only with the cells exhibiting high forward angle light scatter as determined by flow cytometry. Additionally the activity was unaffected by the removal of plastic‐adherent cells from the effector population.In this study, YSNC cells are also examined for the presence of a variety of lymphocyte antigens. The effector cells, as well as the total YS population, were found to lack Lyt‐1, Lyt‐2, Thy‐1, Ly‐5, NK‐1, Qa‐5, asialo GM1, and H‐2 antigens. While these experiments demonstrate the YSNC cells to be distinct from the NK cells of the adult, they do not rule out a potential common lineage for the two natural cytotoxic cell types.