bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular selection of human antibodies with an unconventional bacterial B cell antigen.
Authors: Sasano M , Burton D R , Silverman G J 
Published: December 2022

Abstract
Unconventional Ag for B cells that are comparable to known superantigens for T lymphocytes have not been well characterized. However, the bacterial membrane protein, Staphylococcal protein A (SpA), has sites that interact with the Fab of many IgM, IgA, IgG, and IgE, and in recent reports we have provided evidence of VH restriction in Fab that bind SpA. To investigate the molecular basis for this Fab binding specificity, we have selected monoclonal Fab from a phage-display combinatorial Ig library, based on the ability to bind SpA. By this approach, in an unselected human polyclonal IgG Fab library, about 17% of antibody-expressing clones were found to bind SpA. SpA binding was completely restricted to Fab with VH3 H chains, and about 60% of VH3 Fab in the unselected library had SpA binding capacity. Analysis of 21 VH sequences and 6 VL sequences demonstrated that Fab that bind SpA use diverse VH3 genes, while the L chains derive from a variety of V kappa and V lambda gene families. By creation of antibodies with differential H-L chain pairing, the global capacity to bind SpA was shown to be dictated by VH3 usage, but different L chain usage could result in up to a fourfold change in binding affinity. The apparent KD of the SpA binding by different Fab ranged from 2.5 x 10(-7) to &gt; 10(-5) M. Furthermore, repeated rounds of in vitro panning selected for antibodies based on higher binding affinity. These data indicate that the pattern of VH family restriction of Ig reactive with SpA is comparable to known superantigens, and there is a hierarchy within the binding affinities of VH3 Fab based on V gene usage.
Bacterial superantigens induce rapid and T cell receptor V beta-selective down-regulation of L-selectin (gp90Mel-14) in vivo.
Authors: Miethke T , Wahl C , Holzmann B , Heeg K , Wagner H 
Published: December 2022

Abstract
Upon challenge of mice with bacterial superantigens such as staphylococcal enterotoxin B, several facets of TCR V beta-selective acute T-cell alterations can be observed, which include acute T cell priming, and systemic lymphokine release followed by ligand-specific unresponsiveness. Prompted by experiments showing that stimulation of T cells by phorbol esters in vitro results in rapid shedding of the L-selectin homing receptor, we investigated the expression of adhesion molecules on superantigen-responsive T cells in vivo. Here we show that bacterial superantigens cause TCR V beta-specific loss of L-selectin. Down-regulation of L-selectin was selective, since the expression of other lymphocyte surface receptors was not changed. L-Selectin down-regulation represents a superantigen-induced immediate cell surface alteration and was not observed on T cells stimulated by TCR-specific antibodies. Loss of expression was almost complete within 30 min, and recovered 50 h after challenge. The results suggest that acute loss of L-selectin is a hallmark of T cell activation by bacterial superantigens that may result in profound changes of T lymphocyte recirculation pathways.
The inhibition of different T cell lines specific for the same antigen with TCR antagonist peptides.
Authors: Snoke K , Alexander J , Franco A , Smith L , Brawley J V , Concannon P , Grey H M , Sette A , Wentworth P 
Published: December 2022

Abstract
To further understand and evaluate the phenomenon of TCR antagonism, we wished to determine whether analogs of an antigenic determinant could antagonize a specific polyclonal response. To this end, the ability of TCR antagonist peptides to inhibit a panel of five different DR4w4-restricted, influenza hemagglutinin 307-319-specific T cell lines was examined. An analysis of their V beta and J beta usage indicated that each of these five T cell lines expressed different TCR. A series of HA 307-319 single amino acid substituted analogs were used to determine the fine Ag specificities of the different lines. Ag analogs that demonstrated little or no stimulatory capacity were then examined for their ability to act as TCR antagonists by inhibiting the proliferative response of these five lines. Overall, 17 different peptide analogs capable of antagonizing at least one T cell line were identified. Although no single analog was capable of inhibiting all five T cell lines, two different analogs were identified that were capable of inhibiting four of five of the T cell specificities examined.
Comparative accessory cell function of human peripheral blood dendritic cells and monocytes.
Authors: Thomas R , Davis L S , Lipsky P E 
Published: December 2022

Abstract
The capacity of human peripheral blood (PB) dendritic cells (DC) and monocytes to facilitate T cell activation and the interaction molecules employed were compared. We have shown that precursors of DC constitute 2 to 3% of circulating PBMC, and can be isolated as CD33+CD14dim cells, whereas monocytes are CD33+CD14bright. Freshly obtained DC expressed similar densities of HLA-DR and the accessory molecules LFA-3, ICAM-1, and B7 as monocytes; after a 36-h incubation the expression of HLA-DR, ICAM-1, and B7 increased on both APC. Accessory cell function was examined in PB T cell cultures stimulated by suboptimal concentrations of immobilized mAb to CD3, and by stimulation of an allospecific T cell line. Freshly isolated monocytes and DC were comparable accessory cells in these assays, but their accessory function was increased by in vitro preincubation, although cultured DC and monocytes were comparably active. In contrast, DC were much more effective stimulators of freshly isolated allogeneic T cells than monocytes. DC were much more effective stimulators of freshly isolated allogeneic PB CD4+ naive and memory T cells than monocytes, whereas DC and monocytes were comparable accessory cells for memory and naive T cells stimulated with immobilized anti-CD3. The accessory molecules ICAM-1, LFA-3, and B7 were used comparably by DC and monocytes for accessory function in the presence of immobilized anti-CD3 and in the MLR, and none was unique for either APC population. These accessory molecules costimulated T cells in an additive fashion. Although immature blood DC and monocytes expressed minimal B7 and did not utilize it as an accessory molecule, B7 played an important role in the increased accessory function of differentiated APC. The results indicate that PB DC and monocytes function most efficiently after differentiation into mature cells that express increased amounts of MHC and other accessory molecules. Because DC and monocytes exhibit comparable accessory function in anti-CD3 T cell stimulation, differences in the expression of MHC molecules and/or their bound peptides are likely to explain the markedly enhanced capacity of DC to stimulate allogeneic PB T cells.
IL-2 stimulation of T lymphocytes induces sequential activation of mitogen-activated protein kinases and phosphorylation of p56lck at serine-59.
Authors: Watts J D , Welham M J , Kalt L , Schrader J W , Aebersold R 
Published: December 2022

Abstract
p56lck, a member of the src family of non-receptor protein tyrosine kinases, is expressed almost exclusively in cells of lymphoid origin. p56lck is known to associate with the T lymphocyte surface glycoproteins CD4 and CD8, and plays a critical role in both T lymphocyte development and activation. p56lck also associates with the beta-subunit of the IL-2R, and is activated when IL-2 binds to its receptor. Using primary cultures of Con A-activated normal splenic mouse T lymphocytes, we observed an IL-2-induced sequence of events involving p56lck. We saw a rapid (within 1 to 2 min) and transient increase in p56lck kinase activity, which preceded the activation of both the p42erk-2 and p44erk-1 mitogen-activated protein kinases, maximal activation of which was observed after 10 min. We also observed an IL-2-induced shift in the electrophoretic mobility of p56lck from an apparent molecular mass of 56 kDa (p56lck) to 60 kDa (p60lck), which reached a maximum at 15 min, the level of p60lck remaining constant for up to 4 h thereafter. This IL-2-induced shift correlated with the phosphorylation of serine-59 of p56lck, a site that mitogen-activated protein kinases are capable of modifying in vitro. The implications of these results for the understanding of both p56lck function and lymphoid cell receptor signaling pathways are discussed.
Structure and genomic organization of immunoglobulin light chain in the channel catfish. An unusual genomic organizational pattern of segmental genes.
Authors: Ghaffari S H , Lobb C J 
Published: December 2022

Abstract
Channel catfish L chain cDNA was obtained through a PCR strategy and used to isolate multiple L chain clones from cDNA and genomic libraries. Sequence analysis of full-length cDNA indicates that the V region is preceded by a leader peptide, and represented by framework and CDR regions. Both VL and CL domains contain the invariant cysteines and tryptophans as well as other phylogenetically conserved L chain residues. The sequence similarity of the catfish L chain with higher vertebrate kappa- and lambda-chains, however, does not readily allow the catfish L chain to be classified. Eight cDNA clones isolated from a cDNA library were shown to represent different processed derivatives of sterile L chain transcripts. These transcripts share a similar upstream sequence region and extend downstream to include a CL or alternatively a JL segment in partial germ-line configuration that has been spliced into a CL. Sequence comparisons indicate that these transcripts represent the product of different L chain loci. Genomic Southern blot analyses with VL and CL probes indicate that there are at least 30 VL segments and at least 15 CL segments. The analysis of 17 genomic L chain clones showed that each hybridized with VL-, JL-, and CL-specific probes. Characterization of the gene segments in three of these clones indicates a previously undescribed pattern of segmental gene organization. Gene segments are found in clusters with VL, JL, and CL segments in each cluster. Within a cluster VL segments reside upstream of single copies of closely linked JL and CL segments. The proximity of VL segments downstream from JL-CL segments suggests that individual clusters may be closely linked. The VL segments are located in opposite transcriptional polarity relative to the JL and CL gene segments, which indicates that VL segments are likely rearranged to JL-CL segments by inversion rather than deletion events.
Characterization of a C3 receptor on the envelope of Schistosoma mansoni.
Authors: Silva E E , Clarke M W , Podesta R B 
Published: December 2022

Abstract
The surface of the syncytial epithelium of the human parasite, Schistosoma mansoni, consists of an apical plasma membrane (APM) and an overlying envelope (En). The rapid turnover of these membranes is an adaptation to parasitism and is influenced by ambient signals emanating from the host's immune system. The third component of complement (C3) has been shown to stimulate the synthesis of the En via a C3-binding protein (C3bp) and a Ca(2+)-dependent signal transduction mechanism. Using ELISA the C3bp was found to be restricted to the En. In addition, cross-linking of iodinated C3 to En proteins with the homobifunctional noncleavable disuccinimidyl suberate reagent yielded a receptor-C3 complex in excess of 250 kDa, and SDS-PAGE analysis of solubilized En proteins that were radiolabeled and chromatographed on C3-Sepharose revealed a 130-kDa protein that specifically bound to the C3 beads. In further experiments, using a photoactivatable radiolabeled cross-linker, the Denny-Jaffe reagent, C3 transferred the radiolabel to a 130-kDa En protein. Metabolic labeling experiments have demonstrated that this C3bp is synthesized by the parasite and, more importantly, antibodies raised against the C3bp blocked En synthesis in vivo. Also, the surface localization of the C3bp was demonstrated using immunolabeling electron microscopy. The data presented herein strongly suggest that the 130-kDa schistosome En protein is a C3bp responsible for renewal of the En in response to C3 binding.
IFN inhibits inflammatory responses and protective immunity in mice infected with the nematode parasite, Nippostrongylus brasiliensis.
Authors: Urban J F , Madden K B , Cheever A W , Trotta P P , Katona I M , Finkelman F D 
Published: December 2022

Abstract
Mice infected with the gastrointestinal nematode parasite Nippostrongylus brasiliensis (Nb) develop responses associated with enhanced production of IL-4 (increased serum IgE levels and intestinal mucosal mastocytosis) and IL-5 (tissue and peripheral blood eosinophilia). The antagonistic effects of IFN on IL-4-mediated responses prompted an examination of the effects of IFN on the host response to Nb. Treatment with rIFN-alpha and rIFN-gamma induced a marked increase in parasite egg production (fecundity) in BALB/c mice infected with Nb and delayed intestinal expulsion of adult worms. Treatment with rIFN-alpha or rIFN-gamma also inhibited the rise in peripheral blood eosinophilia that follows inoculation with Nb, and the intensity of pulmonary perivascular tissue eosinophilia. However, Nb-induced increases in serum IgG levels and intestinal mastocytosis were only temporarily delayed by IFN. Induction of endogenous IFN production by injection of fixed Brucella abortus into mice infected with Nb also resulted in an increased worm fecundity and delayed adult worm expulsion. These effects were ablated when mice given Brucella abortus also received injections of neutralizing anti-IFN antibodies. Thus, IFN inhibit host protective immunity to Nb, perhaps by interfering with the production and effects of Th2 cytokines.
CD4+ type 1 and CD8+ type 2 T cell subsets in human leishmaniasis have distinct T cell receptor repertoires.
Authors: Uyemura K , Pirmez C , Sieling P A , Kiene K , Paes-Oliveira M , Modlin R L 
Published: December 2022

Abstract
The mechanism of protective immunity and immunologic resistance against intracellular pathogens is believed to involve the activation of Ag-specific T cells. The T cells involved in protection/resistance to Leishmania can be studied using localized American cutaneous leishmaniasis (LCL) as a model, because the disease is often self-healing. Our study was undertaken to identify specific T cell populations that had accumulated in LCL lesions on the basis of TCR V beta gene usage. RNA was derived from skin lesions and blood of eight LCL patients, as well as from purified CD4+ and CD8+ subsets from the lesions and blood of three patients. After synthesis of cDNA, V beta gene usage was assessed by polymerase chain reaction. In all eight patients, several V beta gene families were overrepresented in lesions compared to blood. More importantly, the TCR V beta repertoires of both lesional CD4+ and CD8+ subsets were skewed compared to the repertoire of the respective subsets in the blood of the same donor. The overrepresented V beta s in the CD4+ and CD8+ subsets from lesions were in most instances disparate, particularly with the V beta 6 TCR skewed in the lesional CD8+ subset. Not only were the TCR repertoires of the overrepresented V beta in the lesional CD4+ and CD8+ subsets generally distinct, but the cytokine mRNA expressed by these subsets were also discrete. Strikingly, the CD4+ subset was characterized by IFN-gamma mRNA expression and the CD8+ subset by IL-4 and IL-10 mRNA expression. These data indicate that the pathogenesis of human leishmaniasis may be explained by the balance of CD4+ type 1 and CD8+ type 2 T cells, which probably recognize distinct sets of Ag.
Association of all three types of Fc gamma R (CD64, CD32, and CD16) with a gamma-chain homodimer in cultured human monocytes.
Authors: Masuda M , Roos D 
Published: December 2022

Abstract
Receptors for the Fc region of IgG (Fc gamma R) on mononuclear phagocytes have been shown to play an important role in the removal of IgG-opsonized particles from the circulation. We found that all three types of Fc gamma R (CD64, CD32, and CD16) in cultured human monocytes are associated with the gamma-chain homodimer that is also present in the high affinity receptor for IgE. Immunoprecipitates of each of these Fc gamma R, prepared from 1% digitonin lysates of cultured human monocytes, incorporated phosphate into a gamma-chain homodimer when incubated with [gamma-32P]ATP. Fc gamma RII immunoprecipitates also incorporated phosphate into Fc gamma RII itself. When human alveolar macrophages were used, similar results were obtained. Although to a minor extent, each anti-Fc gamma R immunoprecipitate from freshly purified monocytes also coprecipitated gamma-chains. These Fc gamma R and gamma-chains did not constitute one large complex, because anti-Fc gamma RI or anti-Fc gamma RIII immunoprecipitates did not coprecipitate Fc gamma RII. In addition, F (ab')2 fragments of anti-Fc gamma R mAb bound to intact cells were recovered in the anti-gamma-chain immunoprecipitates but not in immunoprecipitates made with anti-Fc gamma RIII or anti-Fc gamma RII mAb. When recovery of radioactivity in anti-gamma-chain immunoprecipitates was compared with that in anti-mouse-Ig immunoprecipitates, approximately 25% of the Fc gamma RI and 20% of the Fc gamma RII expressed at the cell surface were associated with gamma-chains. The gamma-chains may play an important role in signal transduction via Fc gamma R in human macrophages.
Mature CD4+ T lymphocytes from MRL/lpr mice are resistant to receptor-mediated tolerance and apoptosis.
Authors: Bossu P , Singer G G , Andres P , Ettinger R , Marshak-Rothstein A , Abbas A K 
Published: December 2022

Abstract
The goal of this study was to examine the functional responses and tolerance susceptibility of T lymphocytes from mice of the autoimmune strain, MRL/lpr. A population of autoreactive CD4+ T cells can be readily expanded from the lymphoid tissues of young lpr mice. Lines of IL-2-producing autoreactive and alloreactive lpr and alloreactive +/+ T cells were developed to study their responses to tolerance-inducing stimuli. Culture of +/+ T cells with high concentrations of immobilized anti-CD3 antibody induces both functional anergy and apoptosis. By contrast, lpr-derived T cell lines are relatively resistant to anergy and apoptosis. The implications of these findings for the development of autoimmunity, and the possible role of the Fas Ag in determining resistance or susceptibility to tolerance, are discussed.
Use of C6-deficient rats to evaluate the mechanism of hyperacute rejection of discordant cardiac xenografts.
Authors: Brauer R B , Baldwin W M , Daha M R , Pruitt S K , Sanfilippo F 
Published: December 2022

Abstract
C plays a critical role in the hyperacute rejection (HAR) of discordant xenografts (Xg), but the relative contribution of early vs late C components is unknown. In this study, genetic differences in C6 activity were correlated with HAR of guinea pig cardiac Xg by the rat. Seven rat strains were tested for C activity. Six strains (PVG.R1 (R1), PVG.1A (1A), DA, W/F, F344, LEW) had readily detectable C activity in the total and alternative pathways. Some PVG rats also had adequate C activity [PVG (C+)] but others [PVG (C-)] had a profound C6 deficiency. All rats with adequate C activity (n = 35) rejected cardiac Xg between 15 and 80 min. PVG (C+) (n = 6) rats also rejected cardiac Xg hyperacutely (26 +/- 12 min), whereas PVG (C-) (n = 16) rats, which had high preformed IgM natural antibody titers, rejected cardiac Xg in 1 to 2 days (2678 +/- 542 min). Transfer of serum from R1 rats to PVG (C-) recipients with vigorously beating Xg caused HAR of cardiac Xg within 116 +/- 75 min. Transfer of fresh PVG (C-) serum or heat-inactivated R1 serum did not induce HAR. HAR was characterized by intravascular platelet aggregation and interstitial hemorrhage, whereas Xg transplanted to PVG (C-) recipients had patent vessels at 30 min but were heavily infiltrated by granulocytes and monocytes at 2 days. These findings indicate that a deficiency in C6 prevents HAR but allows an accelerated acute rejection that may be mediated by the generation of vasoactive and chemotactic C3a and C5a.
Regulation of anti-Sm autoantibodies by the immunoglobulin heavy chain locus.
Authors: Halpern M D , Craven S Y , Cohen P L , Eisenberg R A 
Published: December 2022

Abstract
Anti-Sm antibodies are specific markers for systemic lupus erythematosus in MRL mice and in humans. The prevalence of anti-Sm positivity in inbred MRL/Mp-lpr/lpr(MRL/lpr) mice is consistently about 25% at 5 mo of age, when the disease is at its peak. The control of the development of anti-Sm in individual MRL/lpr mice has been shown to be the result of stochastic factors, and previous research has indicated that the immunoglobulin heavy chain (IgH) b allotype may be more amenable to the production of anti-Sm. We have now further investigated the influence of the IgH genetic locus on the production of anti-Sm and other autoantibodies in an allotype congenic MRL strain, the MRL/Mp-Ipr/Ipr-IgHb (MRL/lpr-IgHb). Strikingly, 78% of MRL/lpr-IgHb mice produced anti-Sm, compared with 27% of contemporaneous MRL/lpr (IgHj) mice. Of those mice that were positive for anti-Sm, the MRL/lpr-IgHb strain produced significantly higher levels of anti-Sm than did the anti-Sm positive MRL/lpr mice. No differences were observed between the conventional MRL/lpr and the MRL/lpr-IgHb levels of antichromatin, anti-ssDNA, antiribosomal P, or anti-Su. In addition, kidney function, which was assessed by measuring serum urea nitrogen levels, was similar in the two strains. These results support the notion that the control of anti-Sm production in MRL/lpr mice operates through the IgH locus.