bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for IFN-gamma as a mediator of the lethality of endotoxin and tumor necrosis factor-alpha.
Authors: Doherty G M , Lange J R , Langstein H N , Alexander H R , Buresh C M , Norton J A 
Published: December 2022

Abstract
Current evidence indicates that endogenously produced peptide cytokines, most notably TNF-alpha and IL-1, mediate the lethality of experimental endotoxemia. Because circulating serum levels of IFN-gamma can be detected soon after TNF-alpha and IL-1 in response to endotoxin, we investigated the role of IFN-gamma in endotoxin and TNF-alpha lethality. Specific neutralizing antibodies to murine TNF-alpha (anti-TNF-alpha Ab) or murine IFN gamma (anti-IFN-gamma Ab) produced in our laboratory protected mice against the lethality of Escherichia coli endotoxin (LPS) administered 6 h later. Serum IFN-gamma levels 2 h after i.v. LPS were lower in mice treated with anti-TNF-alpha Ab compared to mice that received nonimmune IgG (median less than 2.5 vs 3.0 U/ml, P2 less than 0.05). In contrast, serum TNF-alpha levels 1 h after i.v. LPS peaked more than fourfold higher in mice treated with anti-IFN-gamma Ab compared to controls (median greater than 6400 vs 1405 pg/ml, p2 less than 0.05). Doses of TNF-alpha (300 micrograms/kg) and IFN-gamma (50,000 U) which were well tolerated when given individually were synergistically lethal in combination (0% lethality vs 100% lethality, P2 less than 0.001), and were associated with higher serum levels of IL-6 than with either cytokine alone. Anti-IFN-gamma Ab provided complete protection against exogenous human rTNF-alpha at the LD100 dose (1400 micrograms/kg, p2 less than 0.001), and in fact prevented lethality at doses four- to fivefold greater than the LD100 human rTNF-alpha (up to 6000 micrograms/kg). We conclude that IFN-gamma is synergistic with TNF-alpha, is essential for the lethality of LPS and TNF-alpha, and may have modulating effects on the negative control of serum levels of TNF-alpha after LPS in mice.
Human low molecular weight B cell growth factor induces surface IgM+/A- B cells to express and secrete IgA.
Authors: Bertolini J N , Bertolini J , Thean E , Benson E M 
Published: December 2022

Abstract
The regulation of Ig class expression has been a controversial area of research. It is well established that T cells, and/or their products, influence which Ig isotype is produced during an immune response. In this study the regulation of Ig secretion of activated human IgM+/A- B cells was examined. Human T cell supernatants induced PWM-activated IgM+/A- B cells to switch to IgA secretion. Purification of the lymphokine mediating this effect involved hydroxylapatite, ion exchange, and gel filtration chromatography. The purified lymphokine could induce switch of IgM+/A- B cells, and it was also capable of inducing proliferation of Staphylococcus aureus Cowan 1 strain (SAC)-activated IgM+/A- B cells. SDS-PAGE and isoelectric focusing indicated the protein mediating this activity had a molecular mass of approximately 14 kDa and a pI of 6.8. These results suggested that the observed activity might be due to low m.w. B cell growth factor (LMW-BCGF), a lymphokine which is capable of inducing proliferation of SAC-activated B cells and has a molecular weight and pI value in the range of the purified protein. Indeed, rLMW-BCGF was able to switch IgM+/A- B-cells to IgA expression and secretion as well as induce the proliferation of SAC-activated IgM+/A- B cells. These results demonstrate that LMW-BCGF is capable of inducing PWM-activated IgM+/A- B-cells to switch to IgA possibly by providing a proliferation signal which induces clonal expansion of IgM+/A- B cells, the progeny of which express a range of isotypes including IgA. This study also demonstrates that lymphokine induced isotype switching involves an intermediate stage of B cell development where human B cells coexpress IgM and a downstream isotype on their surface.
Development of the B cell anti-DNA repertoire in (NZB x NZW)F1 mice. Relationship with the natural autoimmune repertoire.
Authors: Gilbert D , Margaritte C , Payelle-Brogart B , Tron F 
Published: December 2022

Abstract
The relationship between pathologic anti-DNA and natural autoantibodies (Auto Ab) remains unclear. In particular, it has not yet been elucidated whether pathologic anti-DNA antibodies originate from and are regulated by the pool of natural Auto Ab. To address this question, a large number of Ig-secreting hybridomas were derived from the unstimulated splenocytes of B/W mice, newborn to 12 mo of age, and their binding activities against a panel of self-Ag (DNA, actin, tubulin, myosin, and myoglobin), isotype, idiotypic determinants, and VH gene utilization were analyzed. A progressive increase in the number of Ig-secreting clones was observed and associated with a constant proportion (approximately 6%) of autoreactive B cell clones. However, dramatic changes in the pool of autoreactive B cell hybridomas were observed as the disease evolved, including the selective maintenance of IgM anti-DNA polyspecific antibodies, reduction in percentage of polyspecific IgM mAb with no DNA-binding activity, and the production of IgG anti-DNA antibodies of the IgG2 class. The kinetics, immunochemical properties, and idiotypic analysis of polyspecific IgM mAb with DNA-binding activity strongly suggest that they belong to natural Auto Ab and constitute the precursors of pathologic IgG anti-DNA antibodies. In addition, and IgM polyspecific antibody was demonstrated to bind IgG anti-DNA mAb through F(ab')2 interactions suggesting a regulatory role of natural antibodies and their participation in the control of pathologic Auto Ab production.
Comparison of tyrosine kinase activation by mitogenic and nonmitogenic anti-IgD antibodies.
Authors: Brunswick M , Burkhardt A , Finkelman F , Bolen J , Mond J J 
Published: December 2022

Abstract
Low concentrations of anti-Ig dextran conjugates that stimulate very high levels of B cell proliferation and Ig secretion stimulate no detectable increases in tyrosine phosphorylation. To study this point further, we compared tyrosine phosphorylation patterns induced by mitogenic and nonmitogenic anti-Ig antibodies. Whereas the mitogenic, strongly cross-linking, antibody H delta a/1 induced greater levels of tyrosine phosphorylation than did the nonmitogenic antibody FF1-4D5, the pattern of substrate phosphorylation was equivalent. At lower concentrations of H delta a/1, which were still mitogenic, the degree of phosphorylation that was induced was similar to that induced by high concentrations of FF1-4D5. Both antibodies stimulated comparable increases in the kinase activity of the three src-related kinases present in normal B cells and linked to the IgR, i.e., Blk, Fyn, and Lyn. These results suggest that the extent of tyrosine kinase activation is proportional to mIg cross-linking, that induction of B cell DNA synthesis may require little tyrosine kinase activation, and that activation of tyrosine kinase per se does not necessarily lead to B cell DNA synthesis.
Conservation of signal transduction mechanisms via the human Fc epsilon RI alpha after transfection into a rat mast cell line, RBL 2H3.
Authors: Gilfillan A M , Kado-Fong H , Wiggan G A , Hakimi J , Kent U , Kochan J P 
Published: December 2022

Abstract
The high affinity receptor for IgE (Fc epsilon RI) is present on mast cells and basophils, and the aggregation of IgE-occupied receptors by Ag is responsible for the release of allergic mediators. The Fc epsilon RI is composed of at least three different subunits, alpha, beta, and gamma, with the alpha subunit binding IgE. The series of biochemical events linking receptor aggregation to the release of mediators has not been fully delineated. As a step towards understanding these processes, and for the development of functional cell lines, we have transfected the human Fc epsilon RI alpha subunit into the rat mast cell line RBL 2H3. These human Fc epsilon RI alpha-transfected cell lines have been characterized with respect to the association of the human alpha subunit with endogenous rat beta and gamma subunits and the ability of aggregated Fc epsilon RI alpha subunits to mediate a variety of biochemical events. The signal transduction events monitored include phosphoinositide hydrolysis, Ca2+ mobilization, tyrosine phosphorylation, histamine release, and arachidonic acid metabolism. In all cases, the events mediated by aggregating human Fc epsilon RI alpha subunits were indistinguishable from those produced via the rat Fc epsilon RI alpha. These results demonstrate that the human Fc epsilon RI alpha subunit can functionally substitute for the rat Fc epsilon RI alpha subunit during signal transduction. The availability of this cell line will provide a means of evaluating potential Fc epsilon RI antagonists.
Mast cells enhance the antibody-mediated injury of skin basement membrane in mice.
Authors: Zhang Y , Ramos B F , Jakschik B A 
Published: December 2022

Abstract
Immunologic basement membrane injury occurs in certain human diseases. We investigated the role of mast cells in the initiation of inflammation induced by selective deposition of antibody on the basement membrane in the skin. Intradermal injection of the antibody into mast cell-deficient WBB6F1-W/Wv mice and their congenic controls, WBB6F1-+/+, caused C (C3) deposition and tissue damage preferentially at the dermo-epidermal junction (basement membrane). Damage occurred earlier and was more extensive in normal than in WBB6F1-W/Wv mice. Hemorrhage in WBB6F1-W/Wv was reduced by 50%. In both groups of mice, a dose- and time-dependent neutrophil infiltration reached maximum at 8 h. At the peak, neutrophil accumulation in WBB6F1-W/Wv was only 50% of that in normal mice. Mast cell reconstitution of WBB6F1-W/Wv mice normalized the inflammatory response. Pretreatment with a 5-lipoxygenase inhibitor, A-63162, reduced neutrophil infiltration by 60% in normal but not in WBB6F1-W/Wv mice. Mast cell repletion restored the effect of A-63162. The results indicate that mast cells are important for the initiation of inflammation induced by the deposition of antibody on the basement membrane and the production of leukotrienes participating in neutrophil elicitation.
Role of hapten-anchoring peptides in defining hapten-epitopes for MHC-restricted cytotoxic T cells. Cross-reactive TNP-determinants on different peptides.
Authors: Martin S , Ortmann B , Pflugfelder U , Birsner U , Weltzien H U 
Published: December 2022

Abstract
Synthetic hapten-peptide conjugates selectively modify cell-bound MHC class I molecules in a haplotype-specific way. We investigated the contribution of the carrier peptides to the structural specificity of T cell-antigenic TNP epitopes, using different H-2Kb-binding TNP-peptides and a collection of TNP/Kb-specific CTL clones. Adjustment of peptide sequences to the proposed Kb-specific "motif" (octamers with F or Y and L in positions 5 and 8, respectively) enhanced Kb-binding and antigenicity by many orders of magnitude. Moreover, several clones reacted to peptides, containing the "motif" and TNP-lysine in position 4 but were otherwise unrelated by sequence. TNP in other positions was not recognized by these cells, but other CTL reacted to TNP in position 7. This points to the positioning of hapten determinants within the MHC binding groove as a major role of the anchoring peptide. However, determination of the limiting amounts of TNP peptides that elicit antigenicity or inhibit other Kb-restricted CTL reactions revealed that TCR also recognize variations in the sequences of carrier peptides. This contribution is low for TNP in position 4 but high in position 7, indicating lysine in position 4 as a particularly dominant and cross-reactive hapten-anchoring site in Kb-associated peptides. This implies that cell modification with lysine-reactive TNP reagents results in immunodominant, highly repetitive TNP epitopes, which may explain the strong antigenicity and the allergenic properties of TNP, as well as the restricted TCR repertoire directed against this hapten. Our data further recommend hapten peptides for general studies of TCR-Ag interactions because in contrast to pure protein Ag, hapten epitopes tolerate substantial structural variations in the MHC-anchoring peptide, and can be located by hapten-specific antibodies.
Ultrastructures and interactions of complement factors H and I.
Authors: DiScipio R G 
Published: December 2022

Abstract
The human complement regulatory protein, factor H, was examined by high resolution transmission electron microscopy. Results of electron microscopy confirm hydrodynamic analysis and indicate that factor H is a monomer of M(r) approximately 155,000. Factor H is an extended flexible molecule with a contour length of 495 A and a cross-sectional diameter of 34 A. Most images of factor H indicate that its polypeptide chain typically folds back on itself with the result that the average length of a factor H molecule is about half its contour length. Only one end of factor H associates with C3b. When bound to C3b, factor H still shows considerable conformational flexibility. Factor I is a bilobal protein of 130 A in length, and its two globular parts have maximal diameters of 54 and 49 A. The results establish that factor I is a two domain protein where the smaller subunit is a protease and the larger one is involved with binding C3b. Factor I binds C3b with a one-to-one stoichiometry in an ionic strength-dependent fashion. In the absence of sodium chloride an affinity constant of 5.7 x 10(5) M-1 was determined for factor I interaction with C3b. Whereas the Scatchard plot of factor I binding to C3b in the absence of factor H is linear, in the presence of factor H a curvilinear graph is obtained. The strong binding sites on C3b for factor I have an affinity at least 15-fold higher in the presence of factor H than in its absence. The results of both electron microscopy and binding studies were combined to compose a scheme envisioning how factors H and I cooperate for the processing of C3b.
Isolation and characterization of cDNA clones for the mouse thymocyte B cell antigen (ThB).
Authors: Gumley T P , McKenzie I F , Kozak C A , Sandrin M S 
Published: December 2022

Abstract
The Thb locus is responsible for the expression of 15-kDa phosphatidyl inositol anchored molecules (ThB) on murine thymocytes and B cells. Thb expression as detected with mAb is polymorphic on B cells with two alleles, Thbh and Thb1 responsible for the high and low expression of ThB on B cells. The regulatory locus for Thb expression had been mapped with the Ly-6 cluster of genes to Chr 15. In our study we used expression cloning in COS cells to isolate cDNA clones that code for ThB after transfection; the cDNA products react with anti- ThB antibodies, but not with Ly-6A.2, -6B.2, -6C.2, or -6D.2 antibodies. One of these clones, pThB-A contains insert of 702 bases which was sequenced. The translated amino acid sequence has 11 cysteine residues, and together with the absence of potential N-linked glycosylation sites is similar to the structure of the Ly-6 molecules. The nucleotide and amino acid sequences of ThB cDNA were compared to those of Ly-6 genes and the Ly-6 related human CD59 and show clear homology. Finally using interspecies crosses, the structural Thb gene has been mapped to Chr 15; thus both structural and regulatory genes map to a similar site. The genetic map location near Ly-6 and the sequence similarity suggest that Thb and Ly-6 may have been derived from the same progenitor by gene duplication.
Activation of human basophils through the IL-8 receptor.
Authors: Krieger M , Brunner T , Bischoff S C , von Tscharner V , Walz A , Moser B , Baggiolini M , Dahinden C A 
Published: December 2022

Abstract
IL-8 and its structural analogs derived from blood platelets have been proposed as stimuli of IgE-independent basophil activation. In order to clarify the mechanism of action of these peptides, we examined the effects of pure IL-8, connective tissue-activating peptide III (CTAP-III), neutrophil-activating peptide 2 (NAP-2), and platelet factor 4 (PF-4) on blood basophils with and without pretreatment by IL-3, which modulates mediator release. After pretreatment with IL-3, significant histamine release was observed with 10(-8) M and 10(-7) M IL-8 and 10(-7) M NAP-2, but not with the other peptides. At higher concentrations (10(-6) M), however, all IL-8 analogs, as well as the unrelated cationic peptides poly-D-lysine, histone VS, and lysozyme, induced histamine release to variable degrees. Binding and competition studies with [125I]IL-8 revealed specific IL-8R on basophils from a patient with chronic myelogenous leukemia and normal individuals. From 3500 to 9600 receptors with a mean Kd value of 0.15 nM were found on average per chronic myelogenous leukemia and normal basophil, respectively. NAP-2 weakly competed for IL-8 binding. IL-8 and, to a lesser extent, NAP-2 led to a transient rise of cytosolic free calcium concentration ([Ca2+]i), which was independent of a preexposure to IL-3. IL-8 prevented the [Ca2+]i rise induced by NAP-2, but did not influence [Ca2+]i responses to other agonists, e.g. C5a, C3a, or platelet-activating factor. IL-8 induced [Ca2+]i changes and histamine release in IL-3-primed basophils were pertussis toxin sensitive. CTAP-III or PF-4 did not compete for IL-8 binding, did not induce [Ca2+]i changes, and did not influence the [Ca2+]i response to IL-8 and NAP-2. This study shows that IL-8 and NAP-2 activate human basophils by a receptor-mediated mechanism similar to that operating in neutrophils. At high concentrations histamine release can also be induced by cationic peptides by a mechanism that does not involve the IL-8R, and probably depends on cationic interactions.
Localization of IFN-gamma receptor in first trimester placenta to trophoblasts but lack of stimulation of HLA-DRA, -DRB, or invariant chain mRNA expression by IFN-gamma.
Authors: Peyman J A , Hammond G L 
Published: December 2022

Abstract
Trophoblasts do not express MHC class II Ag on their cell surface, but it is not known at which level the regulation of expression of these IFN-gamma-responsive genes occurs. We localized the IFN-gamma R Ag to the trophoblasts of normal human first trimester placenta. As previously shown, treatment with IFN-gamma of short term cultures of placental explants did not induce expression of HLA-DR Ag in trophoblasts. We demonstrated that in situ hybridization with probes for DRA, DRB, and MHC class II-associated invariant chain genes gave no detectable signals for the presence of the corresponding mRNA in cytotrophoblasts or syncytiotrophoblasts of first trimester placenta with or without IFN-gamma. Maternal leukocytes in these placental preparations as well as IFN-gamma-treated HeLa cell control cultures expressed these mRNA. In addition, Northern analysis of RNA isolated from the trophoblast cell line Jar after treatment with IFN-gamma showed that induction of transcription did not occur from the HLA-DRA, HLA-DRB, or invariant chain genes. Jar cells expressed the IFN-gamma R Ag. These data suggest that down-regulation of MHC class II Ag on trophoblasts in the first trimester placenta and in a cell line include a lack of productive intracellular signaling by the IFN-gamma R and maintenance, in a coordinate manner, of low steady state levels of the mRNA encoded by the DRA, DRB, and invariant chain genes.
Role of cathepsin D in antigen presentation of ovalbumin.
Authors: Rodriguez G M , Diment S 
Published: December 2022

Abstract
Modification of protein Ag by proteolysis is one of the principal steps in the presentation of Ag to Th cells. However, little is known about the enzymes participating in these events, their specificity or the characteristics of the natural fragments that they produce. Cathepsin D (CD) is an aspartyl protease identified in endosomes of APC. In this report, the role of CD in the processing of OVA has been investigated. OVA digested in vitro with purified CD was able to stimulate IL-2 secretion by three different OVA-specific I-Ad restricted Th cell hybridomas when it was presented by fixed APC. The digest of OVA was recognized in the context of I-Ad, but not by I-Ak-restricted OVA-specific Th cells. No difference was observed in the ability of OVA digested with CD to stimulate Th cells in the absence of FCS or in the presence of protease inhibitors indicating that extracellular proteases were not likely to contribute to processing of OVA. Taken together, these results suggest that CD is necessary and sufficient for the generation of an antigenic epitope from OVA. A fragment containing the epitope was isolated from the OVA digest by reverse phase HPLC. This fragment, which migrates in SDS-PAGE as a 10-kDa polypeptide, is a potent epitope. Its capacity to activate Th cells is compared to that of the tryptic peptide OVA323-339.
Regulation of transcription of the germ-line Ig alpha constant region gene by an ATF element and by novel transforming growth factor-beta 1-responsive elements.
Authors: Lin Y C , Stavnezer J 
Published: December 2022

Abstract
Inasmuch as transcription of unrearranged, or germ-line, Ig CH genes appears to direct switch recombination, understanding the regulation of this transcription is essential for understanding the regulation of class switching. Transforming growth factor-beta 1 (TGF-beta 1) induces germ-line alpha transcripts and increases class switching to IgA in the I.29 mu B lymphoma and in Peyer's patch and splenic B cells. It has been previously demonstrated that induction of germ-line alpha transcripts by TGF-beta occurs at the transcriptional level in I.29 mu cells. We now demonstrate that the DNA segment located 5' to the initiation sites of germ-line alpha RNA drives expression of a luciferase reporter gene construct in transient transfection experiments. Full constitutive expression requires no more than 106 bp of the 5' flanking segment. By creating a series of deletion and substitution mutations, we have demonstrated that an ATF/CRE site residing within this region is very important for constitutive expression of the germ-line alpha promoter, but mutation of this motif does not diminish TGF-beta induction. Inducibility by TGF-beta requires additional sequences residing between -128 to -106 relative to the first RNA initiation site. Two copies of a tandemly repeated sequence 5' CA-CAG(G)CCAGAC 3' (termed Ig alpha TGF-beta-RE) are located in the region from -127 to -105. An oligonucleotide containing multimers of these repeats confers TGF-beta inducibility to a heterologous promoter. An additional copy of the TGF-beta-RE was identified at -41/-30 and its deletion reduces the TGF-beta response. Thus, we conclude that tandem repeats of a novel TGF-beta-RE are the positive regulatory element for the TGF-beta response. Our study provides further evidence that TGF-beta directs class switching to IgA through induction of transcription of the germ-line C alpha gene and demonstrates that TGF-beta can activate the promoter for the germ-line alpha gene.
Independent and synergistic effects of disulfide bond formation, beta 2-microglobulin, and peptides on class I MHC folding and assembly in an in vitro translation system.
Authors: Ribaudo R K , Margulies D H 
Published: December 2022

Abstract
We have examined the post-translational processing, intrachain disulfide bond formation, folding, and assembly of MHC class I H chains with beta 2-microglobulin after coupled in vitro translation of homogeneous mRNA and transport of nascent chains into canine microsomal vesicles. The formation of native alpha 3 domain conformation was dependent on conditions that optimized intrachain disulfide bond formation, and efficient folding of the alpha 1 alpha 2 domain required exposure to antigenic peptide. beta 2-microglobulin and peptide acted synergistically in forming native alpha 1 alpha 2 domain structure, and a small proportion of molecules with native alpha 1 alpha 2, but non-native alpha 3 structure were detected, indicating that alpha 3 domain folding is not an absolute prerequisite for the formation of native alpha 1 alpha 2 domain structure.