bluuebunny/crossref_metadata_2025_split huggingface dataset:
Defective assembly of class I major histocompatibility complex molecules in an embryonic cell line
Authors: Bikoff Elizabeth K. , Otten Gillis R. , Robertson Elizabeth J. 
Published: March 2007

AbstractDevelopmentally regulated expression of the products of the major histocompatibility complex (MHC) is thought to play a key role in maternal tolerance of the fetal allograft. Here we analyze a cell line (EE2H3), derived from early post‐implantation‐stage mouse embryos, that is defective for MHC class I assembly. To follow expression of a single well‐defined class I product, we introduced the H‐2Dd gene under control of the human β‐actin promoter. We found that the transfected EE2H3 cells expressed abundant levels of H‐2Dd heavy chains and β2‐microglobulin protein, but only small amounts of H‐2Dd surface protein. Surface expression was rescued by the addition of an appropriate antigenic peptide, or by culturing the cells at low temperature. The phenotype exhibited by EE2H3 is thus remarkably similar to that described for class I‐negative somatic cell variants selected using antibodies and complement. However, a striking difference was that surface expression in H‐2Dd‐transfected EE2H3 cells was markedly enhanced in response to treatment with interferon. Thus, we have identified a novel class I assembly‐defective cell line. Considering that EE2H3 was established from primary cultures of mouse embryo cells without immunoselection, and is therefore likely to represent a cell population normally present in post‐implantation‐stage embryos, these findings raise the possibility that expression of class I surface antigens during early development may in part be controlled post‐translationally at the level of MHC class I assembly.
Biased VH gene expression in murine CD5 B cells results from age‐dependent cellular selection
Authors: Andrade Luiz , Huetz François , Poncet Pascal , Thomas‐Vaslin Véronique , Goodhadt Michéle , Coutinho Antonio 
Published: March 2007

AbstractFlow cytometry‐purified, peritoneal and splenic CD5+ and CD5− B cells from neonatal and adult C57BL/6 mice were studied for expression of VH and Vx gene families in RNA colony blot assays, and for frequencies of clones secreting antibodies to bromelain‐treated mouse red blood cells (BrMRBC), single‐stranded DNA, trimethyl ammonium and bovine γ‐globulin, by limiting dilution. The results show few overall differences between the two B cell subsets, which both manifest ontogenic D‐proximal VH preferences that are lost with age. Biased VH11 expression in CD5 B cells is high in adult peritoneum and spleen but absent in newborns. It only partly correlates with the selection of anti‐BrMRBC reactivity, which is considerably higher in peritoneum than in spleen. No particular Vx bias was observed in any of the populations studied with the possible exception of Vx22 in peritoneal CD5+ B cells. We conclude that the antibody repertoire expressed by peritoneal CD5+ B cells of adult mice is not the result of a genetic program, but rather the consequence of local, age‐dependent cellular selection mechanisms.
Monoclonal antibodies that block adhesion of B cell progenitors to bone marrow stroma in vitro prevent B cell differentiation in vivo
Authors: Imhof Beat A. , Schlienger Claude , Handloser Klaus , Hesse Barbara , Slanicka Michaela , Gisler Roland 
Published: March 2007

AbstractB cell differentiation requires adhesion of B cell progenitors to bone marrow (BM) or fetal liver stroma. We show that B lymphoid cells can adhere to the BM stroma cell line CS 1.3, in vitro. Two monoclonal antibodies, SAB‐1 and SAB‐2, inhibited the adhesion of a B220+ progenitor B cell line but did not interfere with the binding of cytoplasmic μ‐chain‐positive pre‐B cells or mature B cells to the BM stromal cell line. Injection of both SAB‐1 and SAB‐2 antibodies into pregnant mice reduced by 90% the number of B220+ B lineage cells in the livers of their embryos. Livers from such embryos also were virtually devoid of cells able to give rise to B cell colonies in soft agar cultures (CFU‐preB). Either antibody separately had no effect. Flow cytometry analysis show that SAB‐1 is present on CS 1.3 stroma cells and on a pre‐B cell line while SAB‐2 is present on pro‐B and pre‐B cell lines, but not on CS 1.3 stromal cells. SAB‐1 and SAB‐2 react with different molecules and neither antibody seems to recognize CD44, and adhesion molecule that may also participate in B cell differentiation. Proteinase K and trypsin can digest both SAB‐1 and SAB‐2 antigens from viable cells suggesting that both are cell surface proteins. We propose that antibodies SAB‐1 and SAB‐2 probably recognize novel cell‐cell adhesion molecules, and that these molecules are involved in the interactions between B cell progenitors and stroma cells.
Tolerance to a self peptide from the third hypervariable region of the E chain. Implications for molecular mimicry models of autoimmune disease
Authors: Roudier Jean , Sette Alessandro , Lamont Alan , Albani Salvatore , Karras James G. , Carson Dennis A. 
Published: March 2007

AbstractAs a first step in the analysis of a molecular mimicry model of rheumatoid arthritis, we addressed the question of whether tolerance to self‐major histocompatibility complex (MHC) class II molecules includes tolerance to peptides from the third hypervariable region of their β chain. We studied T cell responses to a peptide from the third hypervariable region of the Esβ chain, Esβ peptide (PEFLEQRRAAVDTYC), in different mouse strains after footpad priming with peptide in complete‐Freund's adjuvant.Strains of mice of the k or d haplotype (B10D2; H‐2d, B10BR; H‐2k) mounted a vigorous T cell response to the Esβ peptide. In mice expressing the Esβ chain either on the cell surface (B10S9R) or in the cytoplasm as free unassociated chain (B10S), no response could be detected. Binding studies using purified MHC class II molecules and competition for antigen presentation showed that the Esβ peptide binds Ak, Ad and As but not Ek. Thus, the nonresponder status of B10S and B10S9R mice appears to reflect self tolerance. Tolerance was also suggested by the observation that responder × nonresponder F1 crosses such as (B10D2 × B10S9R) and (B10BR × B10S9R) did not respond to Esβ peptide.Interestingly, mice derived from the (B10BR × B10S) cross responded to the Esβ peptide, suggesting that the immune system may not always tolerate peptides from the third hypervariable region of self‐MHC class II molecules.
The early cellular and humoral immune response to primary and booster oral immunization with cholera toxin B subunit
Authors: Lewis David J. M. , Novotny Pavel , Dougan Gordon , Griffin George E. 
Published: March 2007

AbstractThe immune response to cholera toxin B subunit given orally was studied in 13 human volunteers. A serum IgG and IgA antitoxin response was observed, which was boosted by a second immunization. Using an immunospot assay, cells spontaneously secreting anti‐toxin IgG and IgA, but not IgM appeared transiently in the blood after immunization. There were 105 IgG‐ and 87 IgA‐secreting cells per 2 × 106 mononuclear cells 7 days after the first immunization, and 282 IgG‐ and 413 IgA‐secreting cells 5 days after the second immunization. A polyclonal increase in total IgM‐secreting cells was observed. Few anti‐toxinsecreting cells were observed in the bone marrow at the peak of the circulating cell response, which could be accounted for by contamination of the sample with peripheral blood, suggesting that the bone marrow is not a significant site of anti‐toxin‐secreting cells after oral immunization.
Immunoregulation of mercuric chloride‐induced autoimmunity in Brown Norway rats: A role for CD8+ T cells revealed by in vivo depletion studies
Authors: Mathieson Peter W. , Stapleton Karen J. , Oliveira David B. G. , Lockwood C. Martin 
Published: March 2007

AbstractMercuric chloride (HgCl2) induces the production of autoantibodies to glomerular basement membrane (GBM) in the Brown Norway (BN) rat. The autoimmune response is self‐limiting and thereafter the animals are resistant to rechallenge with HgCl2. Resistance can be transferred to naive animals by spleen cells from HgCl2‐treated rats. A similar state of resistance can be induced with a low dose of HgCl2, insufficient in itself to induce autoimmunity. We have examined the role of CD8+ T cells in the immunoregulation of this experimental model by depleting this subset in vivo. We have also used inhibition studies in a solid‐phase radioimmunoassay in an attempt to demonstrate any effect of anti‐idiotypic antibodies in the spontaneous resolution of the anti‐GBM antibody response. The initial induction and spontaneous resolution of anti‐GBM antibodies were unaffected by depletion of CD8+ T cells. However, CD8‐depleted animals were no longer resistant to rechallenge with HgCl2. Cell transfer studies showed that spleen cells from CD8‐depleted animals conferred less resistance to HgCl2 than those from animals which had received control antibody. CD8 depletion also reduced the resistance induced by pretreatment with low‐dose HgCl2. Studies in which peak sera were pre‐incubated with post‐recovery sera before testing in a solid‐phase anti‐GBM radioimmunoassay did not support an important role for anti‐idiotypic antibodies. We conclude that CD8+ T cells play an important role in the resistance to rechallenge with HgCl2 in the BN rat, although they are not required for the induction or spontaneous resolution of the initial autoimmune response. Demonstration of the reversal of a suppressive phenomenon in vivo using an anti‐CD8 monoclonal antibody is unusual.
Generation of monoclonal antibodies against soluble human T cell receptor polypeptides
Authors: Devaux Brigitte , Bjorkman Pamela J. , Stevenson Christine , Greif William , Ellio John F. , Sagerström Charles , Clayberger Carol , Krensky Alan M. , Davis Mark M. 
Published: March 2007

AbstractOne approach to the diagnosis and therapy of T cell‐mediated diseases is to develop reagents specific for T cell receptor (TcR) variable (V) regions. To date, however, TcR expressed on the surface of antigen‐specific T lymphocytes have proven to be poorly immunogenic. As a result, few monoclonal antibodies (mAb) recognizing human variable regions are available. In this report, we have used the “phosphatidylinositol linkage” strategy to generate soluble forms of two human allogeneic TcR derived from human cytotoxic T lymphocytes (CTL) known to be specific for HLA‐A2 and HLA‐Aw68/HLA‐Aw69, respectively. Monomeric TcR α and ß chains from the HLA‐A2‐specific CTL were purified in large quantities from CHO cells and each was used to immunize mice to generate mAb. In particular, the anti‐β chain mAb, denoted anti‐Vβ13, stain a significant (≈ 5%) fraction of human peripheral blood α/β T lymphocytes, immunoprecipitate native anti‐A2 TcR molecules, and activate T cells transfected with the relevant α and β chain cDNA. Anti‐α chain mAb were also obtained against a constant region determinant which can immunoprecipitate detergent‐solubilized polypeptides. In general, we find that immunizations with soluble protein are far superior to those with cells bearing TcR chimeras or in combination with the purified protein.
Trypanosoma cruzi: Infection of T lymphocytes and their destruction by antibody‐dependent cell‐mediated cytotoxicity
Authors: Velge Philippe , Kusnierz Jean‐Pierre , Ouaissi Ali , Marty Béatrice , Pham Bach Nga , Capron André 
Published: March 2007

AbstractWe have demonstrated, with optical and transmission electron microscopy, that Trypanosoma cruzi trypomastigotes infect and multiply inside T lymphocytes. The infection rate we have observed in T cells was similar to that seen in the case of macrophage or polymorphonuclear cell infection. Flow cytofluorometric analysis of T lymphocytes purified from mice in the acute phase of the disease, revealed the presence of parasite‐derived antigens on their surface. These antigens appear to be specific to T. cruzi and they could be the result of intracellular parasite antigens as well as adsorption of T. cruzi antigens on the surface of noninfected T cells. Antibodies recognizing these surface antigens were present in both T. cruzi‐infected mouse and human sera. They were able to induce antibody‐dependent cell‐mediated cytotoxicity (ADCC) in the presence of nonimmune mononuclear cells both in autologous and in heterologous combinations. Consequently, we provided evidence suggesting that T lymphocytes could be destroyed during the acute phase of Chagas' disease either by cell infection or by an ADCC mechanism against cells bearing parasite antigens on their surface. Thus, the ability of trypomastigotes to invade T cells may play a crucial role in the immunopathogenesis characteristic of Chagas' disease.
Allospecific recognition of hemic cells in vitro by natural killer cells from athymic rats: Evidence that allodeterminants coded for by single major histocompatibility complex haplotypes are recognized
Authors: Vaage John Torgils , Dissen Erik , Ager Ann , Fossum Sigbjørn , Rolstad Bent 
Published: March 2007

AbstractWe have previously shown that large granular lymphocyte (LGL)‐enriched cell populations have the capacity to spontaneously recognize and kill allogeneic small lymphocytes and bone marrow cells (BMC) in vitro in certain strain combinations of rats. Here, we have studied the alloreactivity of natural killer (NK) cells from PVG nude (RT1c) rats against a panel of major histocompatibility complex (MHC) incompatible hemic cells. Both lymphocytes and BMC from the AO (RT1u), DA (RT1a), BN (RT1n) as well as the MHC‐congenic PVG‐RT1u (RT1u) rat strains were efficiently killed in vitro, whereas cells from syngeneic PVG rats were spared. The structures recognized on lymphocytes and BMC were probably similar since the two cell populations inhibited each other in cross‐competition experiments. A number of features aligned the alloreactive effector cells with NK cells and not T cells. (a) Only about 5% of the effector cells from nude spleens expressed the T cell antigens CD3, CD5 or T cell receptor (TcR) α/β whereas > 50% of the cells expressed markers present on NK cells (CD2, CD8, OX52 and the rat NK cell‐specific marker NKR‐P1 recognized by the monoclonal antibody 3.2.3). (b) The alloreactive cells were granular since pretreatment of nude spleen cells with the lysosomotropic agent L‐leucine methyl ester which eliminated LGL, simultaneously abolished the cytolysis of both allogeneic lymphocytes and YAC‐1 tumor cells. (c) Nude spleen cells stimulated with human recombinant interleukin 2 for 1 week in vitro generated large granular proliferating cells which were CD3−. CD5−, TcR α/β−, but > 95% 3.2.3+. These cells efficiently killed allogeneic hemic cells from the same rat strains as did freshly isolated effector cells. (d) The cytolysis of allogeneic hemic cells could effectively be inhibited with unlabelled NK‐sensitive (YAC‐1 and K‐562), but not NK‐resistant (Roser leukemia) tumor cells.Cross‐competition studies showed that PVG nude NK cells discriminated between AO, BN and DA BMC, suggesting that different alloantigens were positively recognized by subsets of NK cells. The mode of inheritance of the allodeterminant specifically recognized on AO BMC was investigated in crosses and backcrosses between AO and BN or DA rats. A gene dosage effect was observed in that this determinant was expressed at a slightly reduced level in F1 hybrids. Cells from the progeny of a BN × (BN × AO) or DA × (DA × AO) backcross used as inhibitor cells showed that the inhibition of killing of AO target cells co‐segregated completely with the expression of RT1u class I molecules on the inhibitor cells in 22 rats. Taken together, these results have shown that NK cells can recognize allogeneic cells in a specific manner and that one MHC haplotype is sufficient for the expression of at least one of the alloantigens recognized.
Late administration of monoclonal antibody to leukocyte function‐antigen 1 abrogates incipient murine cerebral malaria
Authors: Grau Georges E. , Pointaire Pascal , Piguet Pierre‐François , Vesin Christian , Rosen Hugh , Stamenkovic Ivan , Takei Fumio , Vassalli Pierre 
Published: March 2007

AbstractWe analyzed the role of adhesion molecules in the pathogenesis of experimental cerebral malaria (ECM), since tumor necrosis factor (TNF) plays a major role in this condition and has been shown to up‐regulate in vitro expression of cell adhesion molecules (CAM), particularly intercellular CAM‐1 (ICAM‐1). We found increased expression of ICAM‐1 on brain endothelial cells from mice with ECM. Treatment with monoclonal antibodies (mAb) directed against leukocyte function‐antigen 1 (LFA‐1, the ligand of ICAM‐1) on days 6, 8 and 10 almost totally prevented ECM, while decreasing blood TNF levels. To exclude the possibility that the effects of anti‐LFA‐1 mAb resulted from an even partial inhibition of TNF overproduction, mice with signs of imminent death (hypothermia and neurologic defects) were treated with the anti‐LFA‐1 mAb, with dramatically protective effect. In contrast, injection of anti‐ICAM‐1 mAb on day 6 caused rapid death, while it was innocuous in normal mice. An mAb directed against complement receptor type 3 (CR3) was ineffective, as were injections of soluble human ICAM‐1. These results suggest that adhesion of LFA‐1+ cells to endothelial cells, stimulated by TNF to express high levels of ICAM‐1, is critical in the pathogenesis of ECM. Emergency therapy at interfering with cytoadherence could be considered in the treatment of cerebral malaria in man, in which high blood TNF levels are also observed.
Negative signaling by surface IgM on B cells isolated from ileal Peyer's patch follicles of sheep
Authors: Griebel Philip J. , Davis William C. , Reynolds John D. 
Published: March 2007

AbstractLymphoid follicles from the sheep ileal Peyer's patch (PP) were used to prepare a cell suspension consisting of 98% surface IgM‐positive (sIgM+) B cells and 1% T cells. Co‐stimulation of follicular cells with pokeweed mitogen and either recombinant bovine interleukin 1 (IL 1) or IL 2 resulted in a marked proliferative response. In contrast, the addition of soluble F(ab')2 rabbit anti‐sheep Ig completely inhibited the proliferative response induced by pokeweed mitogen and IL 1 or IL 2 co‐stimulation. Anti‐Ig inhibition of B cell proliferation was specific for ileal PP follicular cells and was not observed with mesenteric lymph node cells or splenocytes. Furthermore, suppression of ileal PP follicular B cell proliferation required at most divalent cross‐linking of sIg was independent of Fc receptors, but was dependent on the concentration of anti‐Ig and required 48 h for maximal effect. Negative signaling by sIgM indicates that ileal PP follicular B cells are functionally distinct from B cells in other secondary lymphoid tissues. Also, the present observations are consistent with previous reports indicating that B cell proliferation in ileal PP follicles is antigen independent.
Germ‐line origin of functional idiotypic interactions: Identification of two idiotypically connected, natural antibodies that are encoded by germ‐line gene elements
Authors: Carlsson Leif , Andersson Åsa , Holmberg Dan 
Published: March 2007

AbstractTwo monoclonal, natural IgM antibodies derived from normal BALB/c mice were selected on the basis of being idiotypically complementary and functionally connected. Nucleotide sequence analysis of their respective heavy and light chain V regions showed that both of the clones expressed VH, D, JH, VL and JL gene segments of germ‐line origin. Furthermore, none of the clones displayed N‐sequence additions. These data suggest a germ‐line origin of a functional idiotypic network and confirm a minimized contribution of somatic diversification through template‐independent addition of N‐nucleotides in neonatal B cell repertoires.
Evidence for an association between human resistance to Schistosoma mansoni and high anti‐larval IgE levels
Authors: Rihet Pascal , Demeure Christian E. , Bourgois Alain , Prata Aluizio , Dessein Alain J. 
Published: March 2007

AbstractThe anti‐larval IgE antibody response of adolescents with high or low resistance to infection by Schistosoma mansoni was evaluated before parasitological cure with oxamniquine and over an extended post‐treatment period during which the least resistant subjects regained high infections. IgE from most sera, taken at several bleeding times before and after treatment, reacted, on immunoblots, with a large number of antigens (Ag) in schistosomular tegument extract. A family of 120‐165‐kDa cross‐reacting molecules and a 85‐kDa Ag were the most prominent Ag. Some of these determinants were shown to be located on the outer tegumental membrane and to be accessible to IgE on living larvae. The comparison of IgE between the two study groups showed that IgE levels were on average six‐ to eightfold higher (p<0.01) in the sera of the most resistant adolescents whereas there was no difference in patterns of Ag recognition between study groups. In contrast to IgE, anti‐larval IgG and IgM levels were either similar in both groups or higher in the least resistant subjects when these exhibited high reinfection levels. IgG that competed for the binding of IgE to larval Ag were detected in most sera and their levels were higher in the least resistant group after reinfection. Finally, the treatment had no observable long‐lasting effects on the levels and on the specificity of the anti‐larval IgE. Altogether, these observations can be taken as evidence supporting a role of IgE in human resistance to infection by S. mansoni.
Chemotaxis of germinal centers B cells in response to C5a
Authors: Kupp Leo I. , Kosco Marie H. , Schenkein Harvey A. , Tew John G. 
Published: March 2007

AbstractAn infiltrate of B cells and plasma cells is characteristic of certain chronic inflammatory lesions. However, mechanisms involved in the local accumulation of these cells have not been established. Efforts to demonstrate that B cells from normal animals can migrate in response to inflammation‐induced chemoattractants have been inconclusive. The objective of this study was to determine if murine germinal center (GC) B cells could respond chemotactically to a C5a gradient. On successive days after secondary immunization, draining lymph nodes were harvested and the activated GC B cells isolated. These GC B cells were placed in modified Boyden chambers, incubated for 3 h and the distance the leading front of cells migrated through the filters was determined. The results show that GC B cells migrated to factors in zymosan‐ and lipopolysaccharide‐activated serum. The migratory response demonstrated distinct kinetics. Cells isolated between 2 to 4 days after secondary immunization migrated, whereas cells isolated at day 0 and beyond day 6 did not. Checkerboard analysis revealed that the migratory response was attributable to both chemokinesis and chemotaxis. Anti‐C5 inhibited the migration of day‐3 GC B cells implicating C5 in the migration mechanism. Studies using recombinant C5a established that this C5 fragment was chemotactically active. In conclusion, GC B cells generally were not chemotactically active. However, at a particular stage of maturation B cells in the GC become responsive to C5a as a chemotactic agent. Thus, B cells from normal animals may respond chemotactically, and C5a may play a role in recruitment of recently activated B cells into inflammatory sites.