bluuebunny/crossref_metadata_2025_split huggingface dataset:
T cell clones expressing the natural killer cell‐related p58 receptor molecule display heterogeneity in phenotypic properties and p58 function
Authors: Ferrini Silvano , Cambiaggi Anna , Meazza Raffaella , Sforzini Sabrina , Marciano Sabrina , Mingari Maria Cristina , Moretta Lorenzo 
Published: March 2007

AbstractA new anti‐p58 monoclonal antibody (mAb), termed CH‐L, has been used to characterize a minor subset of T lymphocytes co‐expressing p58 and CD3 molecules. In two‐color immunofluorescence analysis, CH‐L+CD3+ cells represented 0.5 to 6% of the peripheral blood lymphocytes (in 20 healthy donors). Clonal analysis showed that most CD3+CH‐L+ T cell clones expressed the CD8+4− T cell receptor (TcR) α/β+ phenotype, while only a few were CD8−4+ TcR α/β+, CD8−4− TcR α/β+ or CD8−4− TcR γ/δ+. Western blot analysis indicated that the CH‐L mAb identifies the same 56‐58‐kDa diffuse band in both T and natural killer cell (NK) clones. A minority of T cell clones also expressed other NK‐related markers such as CD16, CD56 and CD94 and two clones also reacted with the anti‐p58 mAb EB6. Interestingly, most clones displayed cytolytic activity in an anti‐CD3 mAb‐triggered redirected killing assay against the Fcδ receptor+ P815 target cells and NK‐like activity against K562 and Raji cells. In contrast, the IGROV‐1 ovarian carcinoma cell line was resistant to cytolysis by all of these clones. Since p58 molecules have previously been shown to exert regulatory functions on NK‐mediated lysis, we investigated whether anti‐p58 mAb could also influence cytotoxicity mediated by CD3+p58+ T lymphocytes. Lysis of P815 target cells, triggered by anti‐CD3 mAb, could be inhibited by anti‐p58 mAb in 8 out of 12 cytolytic clones tested, while 4 clones were not inhibited. In addition, anti‐p58 mAb enhanced the cytolytic activity of 3 clones against IGROV‐1 and of 4 other clones against Raji target cells. Taken together, these data indicate that p58+ T cells express heterogeneous phenotypes and different forms of TcR and, in most instances, display cytolytic functions. Perhaps more importantly, the p58 molecule appears to modulate the cytolytic activity triggered via the CD3/TcR complex.
Healthy monozygous twins do not recognize identical T cell epitopes on the myelin basic protein autoantigen
Authors: Shanmugam Ananth , Copie‐Bergman Christiane , Hashim George , Rebibo Danielle , Jais Jean Philippe , Bach Jean‐Francois , Bach Marie Anne , Tournier‐Lasserve Elisabeth 
Published: March 2007

AbstractThe T cell response against myelin basic protein (MBP) has been extensively studied in humans because of its putative role in the pathophysiology of multiple sclerosis (MS). Higher concordance rates in monozygous twins as well as an increased risk in relatives suggest the role of genetic factors in MS susceptibility. Very little is known about the shaping of T cell repertoire towards self antigens in humans and their contribution to disease susceptibility in autoimmune disorders. Here we report the comparative T cell epitope recognition patterns towards the MBP auto‐antigen in healthy identical twins. We have established MBP‐specific T cell lines from eight sets of twins and characterized their fine epitope specificity. Intra‐pair comparison showed the co‐existence of shared as well as distinct epitopes in six of eight pairs and a complete absence of concordant epitope recognition within two other pairs. These findings indicate that important differences in T cell repertoires against a self antigen may be observed between genetically identical healthy individuals, rendering difficult the interpretation of the differences which may be observed between identical twins discordant for an autoimmune disease.
Major histocompatibility complex regulation of T helper functions mapped to a peptide C terminus that controls ligand density
Authors: Murray Joseph S. , Ferrandis‐Edwards Denise , Wolfe Curtis J. , Schountz Tony 
Published: March 2007

AbstractThe functional status (Th1‐ versus Th2‐like) of CD4 T cells primed against human collagen type IV (hCol IV) or a single 30mer peptide from the α2 chain of this molecule is predicted by the major histocompatibility complex (MHC) class II (I‐A) genotype of the responding mice. H‐2s mice elicit Th1‐like cell‐mediated responses to these antigens, whereas Th2‐like humoral responses are primed in H‐2b,d,k mice. We now report that the ability of MHC to dictate T helper function in this system depends upon a single amino acid of the minimal α2(IV) peptide. The C terminus of this minimal (12mer) peptide is ‐G‐G‐P‐K, which is predicted to form a β‐turn. The present data demonstrate that the terminal lysine (K) stabilizes the immunogens full biological effects necessary for exclusive cellmediated responses in H‐2s mice. The lysine‐truncated (11mer) peptide with otherwise identical sequence effectively primes T helper function in both H‐2b and H‐2s genotypes. Most importantly, our direct analysis of these peptides' presentation by live antigen‐presenting cells (APC) reveals that the 12mer is bound at a log higher density on H‐2s APC than on H‐2b APC, and that the 11mer is presented at an equally low relative density on APC from both genotypes. In vitro analyses of 12mer/11mer cross‐reactive Th clones demonstrate that I‐As restricted clones require about 1–2 log lower doses of 12mer peptide than 11mer peptide to stimulate equivalent thymidine incorporation and cytokine release. By contrast, I‐Ab‐restricted (12mer/11mer cross‐reactive) Th clones show no preference for the 12mer and require relatively high peptide doses similar to those required to stimulate the I‐As clones with the 11mer peptide. Thus, the peptide dose requirements of Th clones reflect the high density of presentation associated with the 12mer: I‐As ligand. Taken together, the results directly support the role of ligand density as an important control point in the functional decision of CD4 T cells.
Interleukin‐1 receptor expression by ovine afferent lymph dendritic cells: response to secondary antigen challenge
Authors: Fiskerstrand Carolyn E. , Hopkins John , Sargan David R. 
Published: March 2007

AbstractInterleukin(IL)‐1 is thought to enhance the function of antigen presenting cells of the dendritic cell lineage. To investigate the interaction of IL‐1 and dendritic cells, recombinant ovine IL‐1α and IL‐1β have been used to determine IL‐1 receptor (R) expression on fresh dendritic cells (ALDC) collected from cannulated sheep pseudoafferent lymph ducts, both prior to and in response to localized ovalbumin challenge. Resting ovine ALDC express ∼ 510 IL‐1R per cell for IL‐1α (Kd ∼ 30 pM) and ∼ 350 IL‐1R/cell for IL‐β (Kd ∼ 160 pM). Saturation binding and in situ analyses show an initial transient but dramatic increase in IL‐1α binding to ALDC by 4 h in response to ovalbumin challenge of primed sheep. Maximal IL‐1R expression, reaching ⩾ 21700 IL‐1R/cell for IL‐1α detected by around 48 h, was followed by a gradual return to resting level by 8 days post challenge. Fewer than 0.5% of resting ALDC expressed IL‐1R but at least 5% of ALDC bound IL‐1α after ovalbumin challenge. There was no evidence of specific up‐regulation of receptors for IL‐1β on these cells. Fresh ovine alveolar macrophages, used as a positive control for specific IL‐1R expression, were found to express ∼ 2600 sites/cell for IL‐1α (Kd ∼ 56 pM) and 16500 sites/cell for IL‐1β (Kd ∼ 4.6 pM). In view of the differing IL‐1 binding characteristics displayed by the receptors on the two cell types, it is postulated that afferent lymph dendritic cells and macrophages are not expressing the same form of IL‐1R.
Development of antibody diversity in single germinal centers: selective expansion of high‐affinity variants
Authors: Ziegner Mike , Steinhauser Gudrun , Berek Claudia 
Published: March 2007

AbstractIn a T cell‐dependent immune response the microenvironment of the germinal center plays a crucial role in the affinity maturation of the antigen‐specific immunoglobulins. In order to look at the development of antibody diversity we have isolated single germinal centers and sequenced light chains characteristic of 2‐phenyl‐oxazolone (phOx)‐specific antibodies. Fourteen days after immunization we can demonstrate various stages of intraclonal diversity. There are germinal centers where B cells are practically unmutated, suggesting that in these cases a substantial clonal expansion has taken place prior to the activation of the hypermutation mechanism. In other germinal centers, sequences with a low number of randomly distributed somatic mutations were observed, indicating that these changes have been introduced recently and/or that they fail to generate high‐affinity variants and hence provide no basis for affinity selection. Finally, germinal centers are found in which practically all sequences carry the amino acid substitutions characteristic of the high affinity phOx antibodies. In these latter cases the high‐affinity variants have been preferentially expanded. We conclude that affinity selection is a process that operates right from the beginning of germinal center development. Those B cells with a relative high affinity for the antigen gain a proliferative advantage over other cells and will dominate the response and these are the cells which will be selected to differentiate into memory cells.
Presentation of exogenous antigens by macrophages: analysis of major histocompatibility complex class I and II presentation and regulation by cytokines
Authors: Magdalena  , Kovacsovics‐Bankowski  , Rock Kenneth L. 
Published: March 2007

AbstractThere is an antigen presenting cell (APC) in the lymphoid organs capable of presenting exogenous antigen (Ag) with major histocompatibility complex (MHC) class I molecules. This study was initiated to isolate clones of these APC to definitively establish their phenotype and to further study their properties. Murine bone marrow macrophages (BM MΦ) were immortalized by overexpressing myc and raf oncogenes. Five BM MΦ cell lines were generated that are phagocytic and expressed at their surface MΦ differentiation Ag. All five cell lines processed and presented exogenous ovalbumin (OVA) with MHC class I molecules. They all presented OVA‐linked to a phagocytic substrate 102–104‐fold more efficiently than soluble Ag. Clonal isolates of two of the MΦ cell lines had an identical phenotype and functional properties as the uncloned lines. These results definitively establish that MΦ are APC with the capacity of presenting exogenous Ag with MHC class I molecules. Interferon (IFN)‐γ interleukin‐4, granulocyte‐macrophage colony stimulating factor and lipopolysaccharide either alone or in combination induced little or no augmentation and in some cases decreased presentation of exogenous OVA with MHC class I. In contrast, all of MΦ activating factors increased MHC class I expression. Moreover, IFN‐γ increased the presentation of cytosolic OVA, demonstrating differences between the presentation of cytosolic Ag versus exogenous Ag with MHC class I. Finally, some lines constitutively processed and presented exogenous OVA with MHC class II while others only presented after stimulation with IFN‐γ. These results demonstrate that the pathways involved in the presentation of exogenous Ag with MHC class I and class II are independently regulated and that a cloned cell is capable of presenting exogenous Ag through both pathways.
Increased Fas antigen expression in murine retrovirus‐induced immunodeficiency syndrome, MAIDS
Authors: Hiromatsu Kenji , Aoki Yoshiyasu , Makino Masahiko , Matsumoto Yoshihiro , Mizuochi Toshiaki , Gotoh Yoshitaka , Nomoto Kikuo , Ogasawara Jun , Nagata Shigekazu , Yoshikai Yasunobu 
Published: March 2007

AbstractThe Fas antigen (Fas), which is a cell surface protein belonging to the tumor necrosis factor receptor family, mediates apoptosis. To assess the contribution of Fas to the pathogenesis of retrovirus‐induced immunodeficiency, we examined the kinetics of Fas expression on the lymphocytes during the course of murine acquired immunodeficiency syndrome (MAIDS) induced by a defective LP‐BM5 murine leukemia virus. The Fas‐positive cells were increased in proportion both in αβ T cells and B cells with the progression of MAIDS. The appearance of Fas‐positive cells in αβ T cells preceeded those in B cells during the course of MAIDS. Among αβ T cells, about half of the Thy1.2+ αβ T cells were positive for Fas, while almost all of Thy1.2− CD4+ αβ T cells were of the Fas‐positive phenotype. The Fas‐positive cells in MAIDS mice, especially unique Thy1.2−CD4+ αβ T cells, were easily rendered apoptotic by stimulation via Fas, indicating that Fas expressed on the lymphocytes is functional. Furthermore, concomitant infection with Mycobacterium avium in MAIDS mice caused a marked increase in Fas‐positive cells accompanied by a severely impaired T cell reactivity to polyclonal stimuli. Taken together, these results suggest the possible participation of the Fas system in the pathogenesis of retrovirus‐induced immunodeficiency.
Adhesion molecules from the LFA‐1/ICAM‐1, 3 and VLA‐4/VCAM‐1 pathways on T lymphocytes and vascular endothelium in Graves' and Hashimoto's thyroid glands
Authors: Marazuela Mónica , Postigo Antonio A. , Acevedo Agustín , Díaz‐González Federico , Sánchez‐Madrid Francisco , De Landázuri Manuel O. 
Published: March 2007

AbstractLymphocytic infiltration of the thyroid gland in autoimmune thyroid disorders requires, as a first step, their attachment to endothelial cells (EC) and, subsequently, their interaction with thyrocytes and extracellular matrix proteins. A number of different ligand molecules have been identified to mediate the interaction between EC and leukocyte subpopulations. In this study, we examined by flow cytometry and immunohistochemical techniques, the expression of integrin receptors and their counter‐receptors by infiltrating lymphocytes and vascular endothelium in thyroid glands from patients with Graves' disease (GD) and Hashimoto's thyroiditis (HT). A high proportion of GD intrathyroidal T lymphocytes expressed the CD69 and gp95/85 (Ea2) activation antigens as well as an increased number of LFA‐αL, VLA‐α1, ‐α4, ‐α5, and ‐β1 integrin receptors, as compared with peripheral blood T lymphocytes from the same patients. The expression of intercellular adhesion molecule (ICAM)‐1 was increased in EC from GD and HT thyroids. In addition, an up‐regulated de novo expression of vascular cell adhesion molecule (VCAM)‐1 was found in EC in GD and HT thyroids, with no reactivity in control thyroids. Dendritic cells in thyroid lymphoid follicles were also positive for ICAM‐1 and VCAM‐1. In addition, most of intrathyroidal mononuclear cells expressed the ICAM‐3 adhesion molecule. This enhanced expression of ICAM‐1 and VCAM‐1 by thyroid EC in GD and HT may reflect their ability to regulate leukocyte trafficking and activation by means of the expression of specific ligand molecules. Our data suggest that both the LFA‐1/ICAM‐1, ICAM‐3 and VLA‐4/VCAM‐1 pathways could play a relevant role in localizing and perpetuating the autoimmune response in the thyroid gland in autoimmune thyroid disorders.
Human IgG isotype‐specific amino acid residues affecting complement‐mediated cell lysis and phagocytosis
Authors: Brekke Ole Henrik , Michaelsen Terje E. , Aase Audun , Sandin Randi H. , Sandlie Inger 
Published: March 2007

AbstractIn this report we describe the construction of anti‐5‐iodo‐4‐hydroxy‐3‐nitrophen‐acetyl (NIP) mouse/human immunoglobulin (Ig)G4 chimeric molecules with altered amino acid residues in the CH2 domain. Three mutants are described: Gln‐268 is substituted by His in γ4 Q268H, Ser‐331 is substituted by Pro in γ4 S331P, and in γ4 Q268H/S331P both residues are substituted. The ability of the mutant molecules to induce complement‐mediated cell lysis (CML) and phagocytosis by FcγRII‐ and FcγRIII‐bearing polymorphonuclear leukocytes (PMN) were measured. In CML, γ4 Q268H was inactive, but both γ4 S331P and γ4 Q268H/S331P were active provided that the antigenic density on the target cells was high. In phagocytosis mediated by PMN, the mutants γ4 S331P and γ4 Q268H/S331P were both active only when complement was introduced. γ4 Q268H was not active in phagocytosis under any conditions. We conclude that His‐268 in human IgG molecules does not modulate CML activity or phagocytosis mediated by FcγRII and/or FcγRIII. Pro‐331 rescues CML activity in IgG4 molecules when the epitope density on the target cells is high, but does not affect FcγRII/FcγRIII‐mediated phagocytosis. In this manner the mutants γ4 S331P and γ4 Q268H/S331P mimic human IgG2. This could indicate a structural similarity between IgG2 and these mutant molecules that distinguish them from both IgG1 and IgG3.
Membrane CD45R isoform exchange on CD4 T cells is rapid, frequent and dynamic in vivo
Authors: Sparshott Sheila M. , Bell Eric B. 
Published: March 2007

AbstractCD4 T cells bearing high (240–190 kDa) and low (180 kDa) molecular mass isoforms of the leukocyte common antigen CD45 define functionally distinct subsets which have been equated with naive and memory T cells. In the rat, CD4 T cells expressing a high molecular mass isoform [identified by monoclonal antibody MRC‐OX22 (anti‐CD45RC)] exchange this for the 180 kDa molecule (CD45RC−) when stimulated by antigen. Here we show, by transferring mature allotype‐marked CD45RC− CD4 T cells (depleted of immature Thy‐1+ CD45RC− recent thymic emigrants) into normal euthymic recipients, that many T cells re‐express the high molecular mass isoform in less than 6 h. By 24 h, 30–60% of CD45RC− CD4 T cells became CD45RC+; within a week the entire cohort appeared to exchange the low for the high molecular mass isoform. Isoform exchange was dynamic and many CD4 T cells returned once again to the CD45RC− state. CD45RC− CD4 T cells declined in number more rapidly than the CD45RC+ subset after transfer. The results suggest that CD45R isoforms distinguish between resting T cells (CD45RC+) and those which have encountered antigen in the recent past. CD45R isoforms would appear to be unsuitable markers of naive and memory T cells.
Viral superantigen‐induced hyporesponsiveness of T cells and polyclonal B cell activation in HIV‐1 infection
Authors: Scott‐Algara Daniel , Lafon Monique , Vuillier Françoise , Pialoux Gilles , Dauguet Charles , Dighiero Guillaume 
Published: March 2007

AbstractThe mechanisms of CD4 depletion and hyporesponsiveness during human immunodeficiency virus (HIV) infection are still unknown. Given the ability of superantigens to stimulate a higher number of lymphocytes than conventional antigens, they may play a major role in this process. Recently, a novel superantigen, the rabies virus nucleocapsid (NC), was described in humans. In the present work, we tested the responses of peripheral blood lymphocytes from asymptomatic HIV‐infected patients to this superantigen. In contrast to its effect in normal controls, NC failed to expand T cells from HIV‐infected individuals expressing the Vβ8 family, and induced a strong decrease in the response to CD3 activation. This absence of response was not the consequence of programmed cell death, and was explained by an anergic state induced by the superantigen. NC superantigen was also able to induce polyclonal activation of B cells, as measured by the secretion of anti‐HIV antibodies and autoantibodies. Moreover, Vβ8 depletion experiments showed that induction of autoantibody secretion was Vβ8 dependent, whereas secretion of HIV‐1 antibody was not. Interleukin secretion studies showed that NC was able to induce high levels of interleukin‐4 and interleukin‐10. Taken together, our results suggest a role for exogenous viral superantigens such as NC in the induction of T cell hyporesponsiveness and polyclonal B cell activation during HIV infection. The induction of a Th2 response and the role of these superantigens in the immunopathogenesis of acquired immunodeficiency syndrome are discussed.
Tyrosine kinase activity associated with the CD7 antigen: correlation with regulation of T cell integrin function
Authors: Chan Anissa S. H. , Reynolds Pamela J. , Shimizu Yoji 
Published: March 2007

AbstractRapid up‐regulation of the functional activity of integrin adhesion receptors is a hallmark of T cell activation. Monoclonal antibody engagement of the CD7 antigen on human T cells results in an increase in β1 and β2 integrin‐mediated adhesion within minutes. This suggests that CD7 is capable of transducing intracellular signals, and is consistent with other indirect studies implicating CD7 as a signaling receptor on T cells. In this report, we have explored the intracellular mechanism by which CD7 modulates integrin functional activity. First, CD7‐mediated up‐regulation of T cell adhesion was found to be unique when compared to phorbol ester stimulation and CD3/T cell receptor cross‐linking, based on differences in the kinetics of activation‐dependent integrin‐mediated adhesion and lack of increase in CD2 functional activity. Second, up‐regulation of integrin activity mediated by CD7 cross‐linking was completely inhibited by the tyrosine kinase inhibitor herbimycin A. Third, antiphosphotyrosine immunoblotting demonstrated that antibody engagement of CD7 results in a rapid but transient increase in tyrosine phosphorylation in human T cells. Finally, CD7 immunoprecipitates contain in vitro kinase activity, as demonstrated by phosphorylation of a predominant band of 80 kDa and multiple other bands. Phosphoamino acid analysis of the 80‐kDa substrate revealed phosphorylation on tyrosine as well as serine and threonine residues. Together, our results suggest that CD7 is associated with tyrosine kinase activity and that this tyrosine kinase activity correlates with the ability of CD7 to regulate T cell integrin functional activity.
Functional cell surface expression by a recombinant single‐chain class I major histocompatibility complex molecule with a cis‐active β2‐microglobulin domain
Authors: Lee Li , McHugh Louise , Ribaudo Randall K. , Kozlowski Steven , Margulies David H. , Mage Michael G. 
Published: March 2007

AbstractAs a preliminary step towards the use of cell surface single‐chain class I major histocompatibility complex (MHC) molecules as T cell immunogens, we have engineered a recombinant gene encoding a full‐length cell surface single‐chain version of the H‐2Dd class I MHC molecule (SCβDdm) which has β2‐microglobulin (β2m) covalently linked to the amino terminus of a full‐length H‐2Dd heavy chain via a peptide spacer. The single‐chain protein is correctly folded and stably expressed on the surface of transfected L cells. It can present an antigenic peptide to an H‐2Dd‐restricted antigen‐specific T cell hybridoma. When expressed in peptide‐transport‐deficient cells, SCβDdm can be stabilized and pulsed for antigen presentation by incubation with extracellular peptide at 27° or 37 °C, allowing the preparation of cells with single‐chain molecules that are loaded with a single chosen antigenic peptide. SCβDdm can be stably expressed in β2m‐negative cells, showing that the single‐chain molecule uses its own β2m domain to achieve correct folding and surface expression. Furthermore, the β2m domain of SCβDdm, unlike transfected free β2m, does not rescue surface expression of endogenous class I MHC in the β2m‐negative cells. This strict cis activity of the β2m domain of SCβDdm makes possible the investigation of class I MHC function in cells, and potentially in animals, that express but a single type of class I MHC molecule.