bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antigen‐specific plaque‐forming cell response of human cord blood lymphocytes after in vitro stimulation by T cell‐dependent antigens
Authors: Van Tol Maarten J. D. , Zijlstra Jitske , Heijnen Cobi J. , Kuis Wietse , Zegers Ben J. M. , Ballieux Rudy E. 
Published: February 2007

AbstractMononuclear cells isolated from human cord blood (CBL) of full‐term neonates were stimulated in vitro with a dose range of T cell‐dependent antigens, i.e. ovalbumin or sheep erythrocytes, and tested for the capacity to mount an antigen‐specific plaque‐forming cell (PFC) response. Both of the antigens used induced in CBL a PFC response with the same kinetics of PFC formation and of the same magnitude as found in cultures of adult peripheral blood lymphocytes (PBL).However, optimal PFC responses in CBL were obtained at a hundredfold lower concentration of the antigens compared with the optimal antigen doses for the induction of a PFC response in adult PBL. This phenomenon was further investigated with respect to the antigen dose dependency of the activation of neonatal B cells and neonatal regulatory T cells. The induction of a PFC response in CBL at antigen concentrations that were suboptimal for adult PBL showed a correlation with the particular antigen dose requirements for the activation of B cells and T helper cells in neonates. Furthermore, the findings suggest that the decrease of the PFC response in CBL stimulated with supraoptimal doses of antigen was not caused by the induction of unresponsiveness at the B cell level or by interference of pregnancy‐associated substances with the PFC response, but was rather the result of the activation of antigen‐specific T suppressor cells. Neonatal T suppressor cells were activated at antigen concentrations that generated T helper activity in the adult. Thus, although neonatal B cells possess the intrinsic capacity to mature into antigen‐specific PFC, the conditions for effective activation of neonatal T cells regulating the B cell response differ from those for the activation of adult regulatory T cells.
Quantitative and qualitative differences in the distribution of HLA class I antigenic determinants in the human thymic compartments
Authors: Stein Harald , Müller Claudia , Ziegler Andreas , Wernet Peter 
Published: February 2007

AbstractThe topographical distribution of HLA class I antigens has been investigated by the immunoperoxidase technique on normal frozen thymic tissue sections with a panel of mono‐ and polymorphic monoclonal anti‐HLA antibodies. HLA class I framework determinants detected by the monoclonal antibody W6/32. HL were present on 80–90% of cortical thymocytes, as well as on all cortical epithelial and medullary cells. However the staining intensity of cortical thymocytes with this reagent was about threefold weaker than that of the medullary thymocytes. Labeling patterns of selected monoclonal antibodies against matching HLA‐A/B allospecificities revealed striking variations in the quantitative expression of certain HLA‐A vs. HLA‐B locus alloantigenic determinants on cortical thymocytes compared to a consistent staining on almost all medullary cells.
Evidence that cytotoxic T cells and natural cytotoxic cells use different lytic mechanisms to lyse the same targets
Authors: Patek Paul Q. , Collins John Leslie , Cohn Melvin 
Published: February 2007

AbstractThere is evidence that natural cytotoxic (NC) cells are in the T cell lineage. To lyse targets, cytotoxic T cells (TK) must recognize any of the myriad antigens plus syngeneic major histocompatibility complex (MHC) determinants. In spite of the evidence which indicates TK and NC are in the same lineage, NC cells can recognize few determinants (perhaps only one) and do not require recognition of MHC determinants.In addition to differences in the requirement for target recognition, in this report we show that TK cells and NC cells also use different lytic mechanisms to lyse the same targets. NC effectors initiate a lytic mechanism in NC‐sensitive and NC‐resistant targets. This lytic mechanism requires approximately 4 h before target lysis is apparent in NC‐sensitive targets; it is inactivated by a protein synthesis‐dependent counterlytic mechanism in NC‐resistant targets. In contrast the TK lytic mechanism causes a rapid release of 51Cr from both NC‐sensitive and NC‐resistant targets and is not inhibited by the NC counterlytic mechanism present in NC‐resistant cells. These findings lead to the conclusion that the mechanism used by NC cells to lyse targets is fundamentally different from that used by TK cells.
Induction of cytolytic T lymphocytes by mitogenic lectins is specifically inhibited by anti‐Lyt‐2 antibodies
Authors: Gullberg Martin , Larsson Eva‐Lotta 
Published: February 2007

AbstractThe effects of anti‐Lyt‐2 antibodies at different levels of lectin‐induced cytotoxic T lymphocyte (CTL) responses have been analyzed. Induction of interleukin 2 (T cell growth factor) reactivity (“step 1”) by three different lectins was profoundly inhibited by anti‐Lyt‐2 antibodies. Also lectin‐dependent cytotoxicity of polyclonally induced CTL was significantly inhibited by anti‐Lyt‐2 antibodies, whereas the interjacent IL2‐dependent proliferation of “step 1”‐induced CTL precursors was unaffected by these antibodies. The anti‐Lyt‐2‐mediated inhibition was selective and specific to the target cell determinants and limited to the events in CTL responses which require interactions with the lectins. These results parallel those obtained in antigen‐induced responses and indicate that antigens and lectins induce CTL responses by interacting with the same type of membrane receptor complex containing Lyt‐2 molecules and antigen‐specific receptors. It follows that T cell mitogenic lectins do not appear to deliver triggering signals through “mitogen” receptors.
HLA class I genes integrated into murine cells are inducible by interferon
Authors: Rosa Frédéric , Le Bouteiller Philippe P. , Abadie Annie , Mishal Zohair , Lemonnier François A. , Bourrel Dominique , Lamotte Michel , Kalil Jorge , Jordan Bertrand , Fellous Marc 
Published: February 2007

AbstractIn human cells treated with interferon, there is an increase in the amount of HLA‐A, B, C mRNA and, to a lower extent, membrane‐bound antigen. However, the mechanism of this mRNA enhancement is still unknown. Using mouse L cells transfected with a unique class I HLA gene, we were able to show that both the related HLA mRNA and protein are increased after murine but not human interferon treatment. Moreover, the discrepancy between interferon‐directed HLA mRNA and protein enhancement is also observed. The mouse transfected cells allowed us to study more precisely the origin of this discrepancy.
Prevention and therapy with electrolectin of experimental autoimmune myasthenia gravis in rabbits
Authors: Levi Giovanni , Tarrab‐Hazdai Rebecca , Teichberg Vivian I. 
Published: February 2007

AbstractElectrolectin (EL), an endogenous β‐D‐galactoside‐binding lectin from Electrophorus electricus, was found to have a prophylactic and therapeutic action on the experimental autoimmune myasthenia gravis (EAMG) in rabbits. EAMG is an autoimmune disease induced by immunization with the purified acetylcholine receptor protein (AChR) and is considered to be a good model for the human disease myasthenia gravis. Simultaneous immunization with AChR and EL completely prevented the onset of myasthenic symptoms. This preventive effect was accompanied by a decrease in the recognition of AChR by anti‐AChR antibodies. The administration of EL to myasthenic rabbits led, in most cases, to a complete recovery which was not accompanied by any significant change in the level of circulating anti‐AChR antibodies. No evidence for an action of EL at the muscular level could be obtained. EL, however, was found to bind to rabbit lymphocytes and to stimulate their mitosis. These results suggest that EL produces its effects on EAMG by acting at the level of the immune system. It is proposed that EL may play a role in the immunological regulation of the response to self‐antigen, which could be one of the biological functions of this animal lectin.
Myeloma class switch variant X63.2aRI‐16 secretes IgG2a and IgG1 with identical VDJ sequence
Authors: Zaiss Siegfried , Beyreuther Konrad 
Published: February 2007

AbstractThe myeloma line X63.2aRI‐16 isolated in vitro as spontaneous tertiary class switch variant (γ1 → γ2b → γ2a → γ2a,γ1) of X63 (IgG1,x) by fluorescence‐activated cell sorting using class‐specific antisera expresses two heavy chains. X63.2aRI‐16 secretes IgG2a,x as does the parental cell line X63.2a‐25, a hybrid molecule containing γ2a and γ1 heavy chains and IgG1,x. The chain of the latter protein is the product of a reverse class switch in regard to the embryonic order of the CH genes. We purified the immunoglobulins of X63.2aRI‐16, isolated the CNBr fragments of both heavy chains and determined the complete amino acid sequence of the VH domains and of the CH domains up to the first subclass‐specific residues. The remaining CNBr fragments of the CH domains were characterized by amino acid analyses. It was found that both heavy chains of the double producer possess identical VH domains and CH domains characteristic for the subclasses γ2a and γ1, respectively. The identities of the two VDJ sequences expressed in X63.2aRI‐16 cells suggest that the reverse class switch event to γ1 cannot simply be explained on the basis of a deletion model involving only a single CH locus.
The chemiluminescence response of human natural killer cells. II. Association of a decreased response with low natural killer activity
Authors: Werkmeister Jerome , Helfand Stephen , Roder John , Pross Hugh 
Published: February 2007

AbstractLow natural killer (NK) responders selected from a panel of 600 normal, healthy volunteers exhibited 5‐ to 10‐fold less cytotoxicity against the human erythroleukemic cell line K562, compared with high NK responders. Antibody‐dependent cellular cytotoxicity against tumor cells, which is mediated by similar or identical effectors, was also depressed in low NK donors whereas lectin‐dependent T cell killing and monocyte‐mediated cytolysis of tumor cells was normal. Low NK donors exhibited normal frequencies of cells expressing the HNK‐1 marker of human NK cells and highly enriched NK fractions were not impaired in their ability to recognize and bind to NK‐sensitive target cells. Interferon partially activated low responder NK cells but did not restore the response to normal levels. The burst of chemiluminescence that is generated by NK cells within seconds of target cell contact was markedly impaired in low NK responder donors. We have previously shown that chemiluminescence detects reactive oxygen intermediates which are necessary but not sufficient for the activation of the NK cytolytic pathway.
Lymphocyte heterogeneity in the trout, Salmo gairdneri, defined with monoclonal antibodies to IgM
Authors: Deluca Dominick , Wilson Melanie , Warr Gregory W. 
Published: February 2007

AbstractA monoclonal antibody to trout serum IgM was tested by immunofluorescence analysis with lymphocytes from thymus, spleen and head kidney. By visual examination, the antibody reacted with only a subpopulation of lymphocytes. The mean values ± SE for positive cells were 5.2 ± 2.3% in the thymus, 30.3 ± 7.9% in the spleen and 12.4 ± 3.0% in the head kidney. Flow cytofluorometric analysis revealed evidence of heterogeneity by size among the membrane IgM‐positive cells of the head kidney and spleen. Depletion of head kidney cells positive for surface IgM by an immune affinity adherence technique of panning, using monoclonal anti‐IgM, significantly reduced the mitogenic response to lipopolysaccharide but not to concanavalin A. It is suggested that this information supports the existence of distinct subpopulations of fish lymphocytes that may be homologous in certain respects to mammalian T and B type cells.
Internalized membrane immunoglobulin meets intracytoplasmic DR antigen in human B lymphoblastoid cells
Authors: Pletscher Martin , Pernis Benvenuto 
Published: February 2007

AbstractThe important role of type II antigens of the major histocompatibility complex (Ia and DR) in the antigen presentation and in the antigen‐specific cooperation between T and B cells is by now firmly established. Human B lymphoblastoid lines MWE and BL were stained with different fluoresceinated anti‐DR antibodies. Not only surface but intracytoplasmic DR structures were brightly stained. The intracellular stain accumulated in a cluster close to the nucleus. Different specificity controls were performed. MWE and BL cells quickly internalize membrane IgM if cross‐linked by corresponding antibodies. The intracellular location of the vesicles containing these complexes showed substantial coincidence with DR‐positive structures in the paranuclear location. It is speculated that IgM‐ligand complexes meet internal DR molecules and are both reexpressed on the plasma membrane to be recognized by primed T cells.
Erythrocyte‐rosette receptor expression by chronic lymphocytic leukemia B lymphocytes
Authors: Guglielmi Paul , Preud'homme Jean‐Louis , Brouet Jean‐Claude 
Published: February 2007

AbstractErythrocyte (E) rosette‐forming cells have been investigated in three patients with B chronic lymphocytic leukemia whose leukemic lymphocytes were easily identifiable. A small percentage of fresh neoplastic cells formed E rosettes in two patients. In every patient, most unstimulated, cultured leukemic lymphocytes became E+ and this was further enhanced by phytohemagglutinin and pokeweed mitogen stimulation or neuraminidase treatment. These E+ B cells lacked detectable T cell antigens (except for a weak expression of an antigen associated with the helper T cell subpopulation in one case). They were unreactive or weakly reactive by immunofluorescence with a monoclonal antibody to the E receptor. However, this antibody completely inhibited E‐rosette formation. The enhanced expression of E‐rosette receptors by in vitro cultured cells appeared to be dependent upon the presence of a small number of E‐rosetting cells at the beginning of the culture. E‐rosette receptor expression by leukemic lymphocytes was most likely in a fourth case (out of 9 patients studied). This finding may account for some of the discrepancies in the study of so‐called T cells in B chronic lymphocytic leukemia.
Constitutive secretion of interleukin 1 by human monocytes
Authors: Treves Abraham J. , Barak Vivian , Tal Tova , Fuks Zvi 
Published: February 2007

AbstractThe constitutive and lipopolysaccharide (LPS)‐induced secretion of interleukin 1 (IL1) by cultured human monocytes and macrophages has been studied. Both freshly obtained monocytes and their culture‐derived macrophages were induced by LPS to secrete similar amounts of IL1. Such induction, however, was accompanied by the secretion of dialyzed inhibitory activity. Constitutive secretion of IL1 was detected in concentrated supernatants of monocyte cultures. The factor obtained constitutively did not manifest significant inhibitory activity. A method is described for the recovery of IL1‐containing supernatants in serum‐ and other stimulant‐free medium. The biological activities of the constitutively secreted IL1 were similar to the LPS‐induced activities.The constitutive secretion of IL1 was not equally distributed in the entire monocyte population. We found that a small fraction of loosely adherent monocytes secreted higher amounts of IL1 than the strongly adherent monocytes. However, the property of higher secretion of IL1 was not stable and disappeared following monocyte cultivation. Thus, constitutive activity of IL1 could be recovered either by concentrating the culture supernatants or by enriching a subset of monocytes with higher IL1 activity.
Different repertoires of mouse T cells for bovine insulin presented by syngeneic and allogeneic cells
Authors: Ishii Norishisa , Klein Jan , Nagy Zoltan A. 
Published: February 2007

AbstractSplenic T cells were primed, after removal of alloreactive cells, to beef insulin on allogeneic antigen‐presenting cells (APC). The fine specificity of in vitro secondary response was tested in combinations H‐2b (responder) T cell‐H‐2k (nonresponder) APC, and vice versa, using separated chains of beef and pork insulin. The response in both combinations exhibited identical specificity patterns demonstrating that both responder and nonresponder APC could present the same array of insulin epitopes to allogeneic T cells. The determinants presented to allogeneic T cells include the A‐chain loop epitope and the B‐chain determinant(s) that were found to be immunogenic for H‐2b and H‐2d T cells, respectively, in the context of syngeneic major histocompatibility complex (HC) molecules. In addition, minor determinants were detected in the A chain outside the loop that are not immunogenic in syngeneic T cell‐APC combinations. Inhibition of T cell proliferation with monoclonal antibodies has shown that class II MHC molecules of the nonresponder (AαkAβk, EαkEβk) as well as those of the responder APC (AαbAβb) are equally capable of presenting virtually all insulin epitopes recognizable by T cells. The data, therefore, demonstrate that the selective recognition of different insulin epitopes observed in syngeneic or semisyngeneic T cell‐APC combinations does not result from determinant selection at the level of APC.
Evidence that the Thy‐1 molecule is the target for T cell mitogenic antibody against brain‐associated antigens
Authors: Jones Barry 
Published: February 2007

AbstractRabbit anti‐mouse brain (RaMBr) antiserum can induce Lyt‐1+, Lyt‐2−, T cells to proliferate and stimulates the same T cell subset to induce B cell proliferation. The aim of this report is to demonstrate that the mitogenic determinant recognized on the T cell surface by RaMBr antiserum is located on the Thy‐1 molecule expressing the products of the Thy‐1a and Thy‐1b alleles. Evidence is drawn from serological and genetic experiments. The brain T cell cross‐reactive, mitogenic determinant is not expressed on Thy‐1− mutants of the BW5147 T cell lymphoma that fail to express the Thy‐1 molecule but do express other T cell surface proteins such as T‐200 and gp 69, 71. Monoclonal anti‐Thy‐1.1 and anti‐Thy‐1.2 antibodies block the binding to the appropriate T cells of the majority of the serum antibody from RaMBr antiserum. The absorption of mitogenic antibody was blocked in a similar fashion, thus demonstrating the close association of the determinant and the Thy‐1 antigen defined by monoclonal alloantibodies. The mitogenic and Thy‐1.1 determinants are probably located on the same molecule because of the data obtained with the BW5147 Thy‐1− mutants and the observation that Thy‐1a T cells, which express a lower level of surface Thy‐1 than Thy‐1b T cells, also express lower levels of the determinant recognized by RaMBr antiserum. Furthermore, in (AKR × DBA/2)F1 mice (Thy‐1a/b) which express less Thy‐1.1 antigen than Thy‐1.2 at the surface, the mitogenic determinant was found to be prefentially associated with Thy‐1.2. The coordinated genetic control of the surface levels of the Thy‐1 determinant and the mitogenic determinant suggests that both determinants are situated on the same molecule in the T cell membrane.
Activation of human B lymphocytes: frequency of antigen‐specific B cells triggered by alloreactive or by antigen‐specific T cell clones
Authors: Lanzavecchia Antonio , Parodi Barbara , Celada Franco 
Published: February 2007

AbstractHuman T cell clones specific for tetanus toxoid (TT) or for alloantigens were isolated and expanded in culture using antigen stimulation and soluble growth factors. When stimulated by the specific antigen, the clones were able to proliferate in the absence of exogenous growth factors and to provide help to B cells. The alloreactive and TT‐specific clones were compared for their capacity to help an anti‐TT as well as a polyclonal antibody response. The frequency of the B cells activated to the production of specific antibody was determined by limiting dilution analysis in cultures containing limiting numbers of responding B cells and optimal numbers of cloned T helper cells. In these conditions a single activated B cell was able to produce about 10 ng of antibody. TT‐specific clones, in the presence of low TT concentrations, selectively induced a number of TT‐specific B cells to produce IgG antibody in the absence of a detectable polyclonal B cell activation. On the other hand the alloreactive clones activated higher numbers of TT‐specific B cells as a part of a strong polyspecific B cell activation. In this case the antibody production did not require the presence of TT in culture; furthermore cells producing antibodies of unrelated specificities were also activated in allostimulated cultures. IgG anti‐TT were produced only by immune donors, while IgM anti‐TT were produced by immune and nonimmune donors, providing the B cells were activated by alloreactive clones.These data demonstrate that human memory B cells can be triggered by both antigenspecific and alloreactive T cells to antibody production. The alloreactive clones can therefore be used to analyze at the clonal level the repertoire of a pool of B cells that contain most, if not all, the memory antibody specificities.
Recirculating and sessile B cell populations in normal and CBA/N mice
Authors: Chaudhuri Monisha , Wallis Valerie J. , Connell Dorothea I. 
Published: February 2007

AbstractChromosomally distinguishable syngeneic mice were parabiosed and the resultant chimerism was followed for 6 weeks in the lymphoid organs, by culturing their cells with polyclonal mitogens, lipopolysaccharide (LPS) for B cells and phytohemagglutinin (PHA) for T cells. As expected of a recirculating population, the T cells equilibrated completely. The B cells in lymph nodes (LN) and Peyer's patches (PP) also equilibrated completely, suggesting that they too are recirculating. B cells in the spleen and blood, however, did not equilibrate over this period. After separation of parabiosed mice, the percentage of partner cells in both the recirculating T and B lymphocyte populations declined steadily, but it continued to rise in the LPS‐responsive populations in spleen and peripheral blood suggesting that they were derived from precursor populations which were themselves chimeric. Injection of lymphocytes into CBA/Ca or CBA/N mice showed that LPS‐responsive populations in LN and spleen localized differently.These results have been interpreted as demonstrating two major populations of LPS‐responsive B lymphocytes in the mouse, one recirculating and the other sessile. The recirculating population appears to be the only LPS‐responsive population in LN and PP. In the spleen, however, the recirculating cells constitute about a quarter of the LPS‐responsive cells, while the rest are sessile cells. The relationship between these two populations has yet to be clarified. CBA/N mice are deficient in both populations but the sessile one appears to be more severely depleted.