bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structure of the VH and VL segments of monoreactive and polyreactive IgA autoantibodies to DNA in patients with systemic lupus erythematosus.
Authors: Kasaian M T , Ikematsu H , Balow J E , Casali P 
Published: December 2022

Abstract
Anti-DNA IgA autoantibodies play an important immunopathologic role in SLE patients. To analyze the cellular origin and the VH and VL structure of anti-DNA IgA autoantibodies, we generated five IgA1 mAbs to DNA using B lymphocytes from three SLE patients. Two mAbs bound to ssDNA only and one to both ssDNA and dsDNA (monoreactive antibodies). The remaining two mAbs bound to DNA (one to ssDNA and the other to both ssDNA and dsDNA) and to other self and foreign Ag (polyreactive antibodies). The IgA mAb relative avidity for DNA ranged from 7.5 x 10(-8) to 8.0 x 10(-10) g/microliters. The anti-DNA IgA mAb used VH segments of the VHI(VI-3b), VHII (VH2-MC2), VHIII (WHG16G and VH26c), and VHIV (V71-2) families in conjunction with V kappa I, V kappa IIIb, or V lambda I segments. All IgA mAb VH segments were juxtaposed with JH4b segments. The heavy chain CDR3 sequences were divergent in composition and length. When compared with those of the closest reported germ line genes, the IgA mAb VH and VL gene sequences displayed a number of differences. That these differences represented somatic point mutations was formally proved in both the monoreactive IgA mAb 412.67.F1.3 and the polyreactive IgA mAb 412.66.F1 VH segments by differential PCR amplification and cloning and sequencing of genomic DNA from the mAb-producing cell lines and autologous polymorphonuclear cells. The sequences of the germ line genes that putatively gave rise to the mAb 412.67.F1.3 and mAb 412.66.F1 VH segments were identical with those of the WHG16G and VH26c genes, respectively. In not only the monoreactive mAb 412.67.F1.3 but also the polyreactive mAb 412.66.F1 and mAb 448.9G.F1 VH segments, the higher concentration of replacement (R) mutations and the higher R:S (silent) mutation ratios in the complementarity-determining region (infinity; 19:0) than in the framework region (1.0) (p = 0.00001, chi 2 test) were highly consistent with selection by Ag. In the five IgA mAb VH and VL segments, the putative and verified somatic point mutations yielded 68 amino acid replacements, of which 38 were nonconserved. Twenty of these yielded positively charged or polar residues that play a major role in DNA binding, including seven Arg, five Lys, three Tyr, two Gln, two His, and a Thr. The conserved amino acid changes included seven Asn. These findings suggest that anti-DNA IgA autoantibodies use a broad selection of VH and VL genes and enhance their fit for Ag by undergoing somatic hypermutation and Ag selection.(ABSTRACT TRUNCATED AT 400 WORDS)
Induction of circulating antagonists to IL-1 and TNF by IL-2 administration and their effects on IL-2 induced cytokine production in vitro.
Authors: Tilg H , Shapiro L , Vannier E , Poutsiaka D D , Trehu E , Atkins M B , Dinarello C A , Mier J W 
Published: December 2022

Abstract
The objectives of this study were to determine whether intensive immunotherapy with IL-2 results in detectable levels of circulating IL-1 and TNF antagonists and whether the levels achieved in vivo are sufficient to affect the generation of secondary proinflammatory cytokines such as IL-1 beta and TNF-alpha. We also sought to determine the extent to which endogenous TNF mediates the generation of an IL-1 antagonist by IL-2-activated PBMCs. In patients undergoing high dose IL-2 immunotherapy, plasma IL-1 receptor antagonist (IL-1ra) levels rose dramatically after the first IL-2 injection, reaching a plateau of 11.03 +/- 0.92 ng/ml within 4 h. TNF-soluble receptor p55 (TNFsRp55) was also detected in the plasma shortly after initiating treatment, and the levels progressively increased throughout the treatment course. PBMCs exposed to IL-2 expressed IL-1ra mRNA and secreted the IL-1ra protein, but neither PBMCs nor neutrophils shed TNFsRp55 in response to IL-2 or supernatants from IL-2-activated PBMCs. IL-1ra at concentrations achieved in the plasma during IL-2 immunotherapy (approximately 10 ng/ml) inhibited the in vitro production of IL-1 beta and TNF-alpha by IL-2-activated PBMCs by 65% and 30%, respectively. Although the monomeric receptor TNFsRp55 at concentrations achieved in the plasma had no effect on the in vitro production of IL-1ra, TNF-alpha, or IL-1 beta, the bivalent TNFsRp75-Fc chimera suppressed the generation of TNF and IL-1. IL-1ra synthesis was unaffected. These results suggest that the amount of IL-1ra generated in response to IL-2 is most likely sufficient to down-modulate the production of proinflammatory cytokines.
Clustering of class I HLA molecules on the surfaces of activated and transformed human cells.
Authors: Matko J , Bushkin Y , Wei T , Edidin M 
Published: December 2022

Abstract
We surveyed cells for the clusters of class I HLA molecules, HLA-I, which we have previously found on JY lymphoblasts. Two fluorescence techniques, fluorescence resonance energy transfer and electron exchange quenching, detected clustered HLA-I molecules on activated normal B and T cells, on cells of B and T lymphoblast lines, and on transformed fibroblasts. No HLA-I clusters were detectable in the surfaces of resting B or T cells or normal fibroblasts. HLA clustering correlates perfectly with the presence of the HC-10 epitope of beta 2-microglobulin (beta 2m)-free heavy chains at the cell surface although not with the amount of this epitope expressed. Clustering was reversed by exogenous beta 2m, but this did not change the amount of HC-10 bound. This suggests that a form of beta 2m-free heavy chain in equilibrium with both native HLA molecules and fully denatured HC-10-positive heavy chains is involved in HLA-I cluster formation.
Cyclic AMP inhibits phosphatidylinositol-coupled and -uncoupled mitogenic signals in T lymphocytes. Evidence that cAMP alters PKC-induced transcription regulation of members of the jun and fos family of genes.
Authors: Tamir A , Isakov N 
Published: December 2022

Abstract
T lymphocyte stimulation via the Ag receptor results in activation of phospholipase C gamma 1 that catalyses the hydrolysis of phosphatidylinositol (PI). The hydrolysis generates inositol phosphate and diacylglycerol, which in turn, increase intracellular Ca2+ concentration and activates protein kinase C, respectively. Agonists operating via the adenylate cyclase pathway or cell permeable cAMP analogues inhibit T cell activation by interfering with the PI-turnover. We have shown that dbcAMP inhibits PI-independent mitogenic signals in T cells after stimulation with TPA plus ionomycin. dbcAMP inhibited the TPA plus ionomycin-induced transcription of IL-2 and IL-2R genes in EL4 cells, suggesting interference with biochemic events downstream to PI hydrolysis and upstream to transcription of early activation genes. Because many of the early genes operating in T cell mitogenesis possess a TPA-response element (TRE) in their promoter region, we tested the effect of cAMP on the TRE-binding protein, TPA-response element (TRE) in their promoter region, we tested the effect of cAMP on the TRE-binding protein, AP-1. dbcAMP increased the binding activity of nuclear proteins consisting of Fos:Jun heterodimers to a TRE-containing oligonucleotide, but altered the composition of Jun proteins in the AP-1. Furthermore, the TPA plus ionomycin-induced transcription program of members of the jun and fos family of genes was altered by dbcAMP, suggesting that inhibition of T cell proliferation by dbcAMP is a consequence of intervention in transcriptional regulation by TRE-binding proteins.
Recognition of a single amino acid change on the surface of a major transplantation antigen is in the context of self peptide.
Authors: Pullen J K , Tallquist M D , Melvold R W , Pease L R 
Published: December 2022

Abstract
The transcripts encoding two strongly alloantigenic class I mutant molecules, Kdm4 and Kdm5, were characterized and found to encode products that differ from the parental Kd glycoprotein by single amino acid substitutions. The Kdm4 molecule has an amino acid change at position 114, an integral component of a beta-sheet associated with pockets D and E of the peptide binding site. The basis for strong alloantigenicity of the variant molecule can be attributed to differences in peptide binding that were visualized by HPLC analysis of eluted peptides. In contrast, the Kdm5 molecule differs from the parent at position 158, a component of the alpha-helix that is not associated with any of the pockets of the peptide binding site. No differences in peptide binding by Kdm5 in comparison with the parent Kd molecule were seen by HPLC, suggesting that the variant and parent molecules bind the same set of peptides. The ability of (dm4 x dm5) F1 hybrid mice to recognize and lyse BALB/c stimulator cells indicates that the alloantigenic properties determined by the 158 substitution result from the interactions of the alpha-helix regions (changed in dm5) with the pockets of the binding site (changed in dm4). We conclude that self peptides shared by the F1 hybrid and the BALB/c stimulator cells are recognized in the context of structural features of the helices of the Ag-presenting molecule as alloantigenic determinants.
Induction of IL-8 gene expression in human polymorphonuclear neutrophils by recombinant IL-2.
Authors: Wei S , Liu J H , Blanchard D K , Djeu J Y 
Published: December 2022

Abstract
Induction of IL-8 gene expression was investigated in IL-2-stimulated circulating peripheral blood polymorphonuclear neutrophils (PMN). Brief exposure of normal PMN to human rIL-2 enhanced both transcriptional and translational expression of IL-8. The IL-8 mRNA was first detectable by 3 h, followed by a continuous maintenance of high mRNA levels up to 18 h. Maximal transcription was obtained with 1000 U/ml of IL-2, which achieved the level observed with known neutrophil-activating factors such as granulocyte macrophage-CSF and Candida albicans. The protein synthesis inhibitor, cycloheximide, had no detectable effect on levels of IL-8 mRNA expression in PMN incubated in medium alone; however, cycloheximide could selectively modulate IL-8 mRNA transcription in PMN, depending on the cytokine used. Cycloheximide did not affect or alter IL-8 mRNA induction in IL-2-treated PMN but abrogated it in granulocyte macrophage-CSF-treated PMN and super-induced the level of IL-8 mRNA in C. albicans-treated PMN. Of significance was the observation that IL-2 has no direct chemotactic effect on PMN, whereas the cell-free supernatants from IL-2-stimulated PMN show potent chemotaxis for freshly isolated PMN, which can be specifically blocked by anti-IL-8 Abs. These findings suggested that the induction of IL-8 gene expression in PMN by IL-2 may be involved in the recruitment of PMN into tissues during local IL-2 therapy in human cancer and in part contribute to tumor rejection.
Regulatory mechanisms for the expression of type IV collagenases/gelatinases in murine macrophages.
Authors: Xie B , Dong Z , Fidler I J 
Published: December 2022

Abstract
The purpose of this study was to determine the regulation of type IV collagenase expression in murine peritoneal macrophages (PEM) after they are incubated with LPS. LPS stimulated the production of the latent forms of 92-kDa (MMP-9) and 72-kDa (MMP-2) type IV gelatinases in a dose-dependent (&gt; 10 ng/ml) and serum-dependent manner. Time course analyses revealed that LPS regulated the expression of MMP-9 and MMP-2 via discordant kinetics. Prolonged treatment of PEM with LPS decreased MMP-9 but not MMP-2 activities. IFN-gamma decreased the production of both gelatinases by PEM responding to LPS. TGF-beta stimulated production of both matrix metalloproteinases but blocked the LPS-mediated secretion of MMP-9. LPS-stimulated MMP-9 production was suppressed by genistein and tyrphostin, two specific tyrosine kinase inhibitors, as well as H-7, a serine/threonine protein kinase inhibitor, but not by HA1004, a relatively selective inhibitor for PKA and PKG. Our data demonstrate that the secretion of MMP-2 and MMP-9 by murine PEM is differentially regulated, suggesting a distinct in vivo role for these two otherwise analogous type IV gelatinases in macrophage-mediated connective tissue destruction at sites of immunologic challenges.
Recombinant and native zymogen forms of human complement factor D.
Authors: Yamauchi Y , Stevens J W , Macon K J , Volanakis J E 
Published: December 2022

Abstract
We have expressed a full-length cDNA clone encoding human factor D by using a baculovirus expression system. The purified recombinant protein reacted with Ab against native factor D, but was hemolytically inactive and slightly larger than factor D. These results suggested that the recombinant protein was the elusive zymogen of factor D. Amino acid sequencing demonstrated that the recombinant factor D consisted of two proenzyme forms with respective activation peptides, AAPPRGR and APPRGR. Catalytic amounts of trypsin converted recombinant profactor D to its enzymatically active form, exhibiting SDS-PAGE mobility and specific hemolytic activity similar to those of native factor D. About 90% of trypsin-activated recombinant profactor D had the same NH2-terminus as factor D. Human thrombin, kallikrein, and plasmin could also activate recombinant profactor D, but relatively high concentrations of these enzymes were required and the specific hemolytic activity of the "activated" profactor D was about one-third that of native factor D. Trypsin-activatable profactor D was also purified from the urine of a patient with Fanconi's syndrome. This native profactor D represented less than 1.0% of the total antigenic factor D in the patient's urine and had a Gly-Arg dipeptide as the activation peptide. Apparently, urine profactor D was produced by cleavage of pre-profactor D at Arg-(-3) by a serine protease with trypsin-like specificity, which probably is different from the putative leader peptidase that produces the recombinant profactor D. Urine profactor D was inhibited by diisopropyl fluorophosphate although the recombinant proenzyme was resistant to this inhibitor.
Specific down-regulation of proliferative T cell alloresponsiveness by interference with CD2/LFA-3 and LFA-1/ICAM-1 in vitro.
Authors: Böhmig G A , Kovarik J , Holter W , Pohanka E , Zlabinger G J 
Published: December 2022

Abstract
T cell activation requires Ag contact with the TCR in the presence of costimulatory signals provided by APCs. When Ag is presented without costimulation, T cells are functionally inactivated. Here we demonstrate that interference with distinct adhesion molecules during Ag contact using mAbs leads to Ag-specific functional inactivation of alloreactive T cells. We found that the presence of a mixture of mAbs specific for CD2, LFA-3, LFA-1 alpha- and beta-chain, and ICAM-1 during primary MLC leads to down-regulation of secondary proliferative responses to Ag from the donor used for priming. Cells from pretreated cultures proliferated well, however, when stimulated with Ag from third party donors, mitogens, or mitogenic CD3 mAb. Because specific reactivity could be restored by addition of IL-2 to restimulation cultures, altered secondary responsiveness appeared to be caused by anergy and not by elimination of specific clones. Furthermore, specific down-regulation of alloresponsiveness was prevented by addition of IL-2 to primary cultures in the presence of mAb. Interference by mAb with either CD2/LFA-3, LFA-1/ICAM-1, CD2/LFA-1, or LFA-3/ICAM-1 had a substantial, though less pronounced effect on secondary responsiveness. After pretreatment with the Ab mixture, CTL generation was substantially but incompletely down-regulated against the original and third party donors. Because a decrease in the reactivity of unstimulated responders by culture was also observed, these findings might be explained by the loss of cytotoxic precursors after culturing under nonstimulating conditions. In conclusion, our data demonstrate that T cells enter a state of anergy when T cell activation is modulated by simultaneous interference with distinct adhesion molecules during Ag contact, which thus might reflect at least partly overlapping functions of particular receptor-ligand pairs in T cell costimulation.
Anti-CD2 mAbs suppress cytotoxic lymphocyte activity by the generation of Th2 suppressor cells and receptor blockade.
Authors: Chavin K D , Qin L , Yon R , Lin J , Yagita H , Bromberg J S 
Published: December 2022

Abstract
The mechanism by which anti-CD2 mAbs inhibit hapten-specific and alloantigen specific CTL was explored. In vivo administration of alpha-CD2 mAbs resulted in 80 to 100% inhibition of alloantigen specific CTLs. Mixing cells from control animals with cells from alpha-CD2-treated groups demonstrated transferable suppression of CTL (40-67% suppression). These suppressor cells were CD4+CD8- and associated with increased IL-4 and TGF-beta in culture as compared with controls. Anti-CD2 mAbs added at the initiation of culture resulted in 60 to 72% inhibition of trinitrophenyl-CTL, whereas mAbs added at the time of assay resulted in less than 50% inhibition of trinitrophenyl-CTLs. F(ab')2 and Fab alpha-CD2 produced inhibition similar to intact mAbs when added at the time of the lytic assay, whereas both produced only modest inhibition in vivo or when added at the initiation of culture. Alloantigen-specific CTLs were not affected by Ab addition to either culture or assay. The immunosuppressive effects were generalizable because a panel of alpha-CD2 mAbs were all comparably effective in suppressing hapten-specific CTLs when administered in vivo. The results demonstrate that the inhibitory effects are the result of blockade of receptor adhesion function during Ag priming or target recognition, Fc-related effects, and the generation of a negative regulatory, CD4+CD8-, IL-4- and TGF-beta-producing TH2 suppressor T cell.
TCR cross-linking induces CTL death via internal action of TNF.
Authors: Wang J , Stohlman S A , Dennert G 
Published: December 2022

Abstract
TCR-mediated stimulation can result in either activation or apoptosis, raising the question of what the mechanisms of these opposing effects might be. Here we demonstrate that microinjection of Ab specific for TNF inhibits activation-induced cell death, implicating TNF in anti-CD3-induced apoptosis. Induction of CTL in the presence of antisense TNF oligodeoxynucleotides inhibits TNF secretion and cell death after stimulation with anti-CD3. Incubation of cells with IL-2 for 48 h before stimulation protects from anti-CD3-induced death, whereas the presence of IL-2 during anti-CD3 treatment is without effect.
The regulatory complex of HLA class I promoters exhibits locus-specific conservation with limited allelic variation.
Authors: Cereb N , Yang S Y 
Published: December 2022

Abstract
The extensive genetic polymorphism of the classical MHC class I molecules provides an important distinguishing feature of the host's immune system. They influence the selection and function of effector cells against tumor and virally infected cells. In these cells, class I molecules are often selectively suppressed. This suppression is locus specific and, in certain cases, allele specific. We analyzed the HLA class I promoter sequences that include class I regulatory complex (CRC) in a total of 41 well-characterized HLA homozygous B lymphoblastoid cell lines, using locus-specific oligonucleotide probes complementary to the overlapping CRC elements. These include kappa B1, kappa B2, IFN response sequence, the putative negative regulatory element, and the HLA counterpart of the H-2RII region that contains the retinoid x receptor beta binding motif. The CRC of HLA promoters displayed locus-specific conservation; however, limited allelic variation was observed in each of the cis elements. In some, variations were apparently generated by gene conversion. The palindromic kappa B1 site, which has an active role in enhancing promoter activity, was found to be conserved in almost all HLA-A and -B alleles, but not in HLA-C. The core DNA binding motif for retinoid x receptor beta was absent within the HLA CRC region. Sequence analysis of promoters from HLA-A31, -B13, and -Cw1 genomic clones, as well as pairwise interallelic and intra-allelic comparison with those of published alleles, showed that locus-specific conservation extended throughout the promoter sequences. Locus specificity and the allelic variation seen in the CRC regions may provide a structural basis for the selective modulation of HLA class I genes.
CD3 delta enhancer. CREB interferes with the function of a murine CD3-delta A binding factor (M delta AF).
Authors: Gupta A , Terhorst C 
Published: December 2022

Abstract
Tissue-specific expression of the murine TCR/CD3-delta gene is regulated by multiple factors. Earlier, we reported that this gene has a tissue-specific enhancer at its 3' end that consists of two cis-acting elements, M delta A and M delta B. This study demonstrates that at least two independent factors bind to the 22 nucleotide long M delta A element. A T cell-specific factor termed M delta AF recognizes a 10-bp sequence TTCCATGACA, whereas the cAMP response element binding protein (CREB) recognizes an overlapping sequence TGACATCA. In vitro studies indicated that the 135-kDa M delta AF and the 43-kDa CREB competed for binding to the M delta A element. To test this competition in vivo, murine T cells (EL4) were cotransfected with a CREB expression plasmid and a reporter plasmid containing the M delta A element. The presence of an excess of CREB protein in the cell inhibited the CAT activity completely. This inhibitory effect of CREB could be overcome by cotransfection of an additional vector containing the somatostatin CRE site that prevented the overexpressed CREB protein from binding to the M delta A element. It is possible that the murine CD3-delta gene in T cells is regulated by the relative levels of the T cell-specific DNA binding protein M delta AF and the ubiquitous CREB in conjunction with other factors.
CD8 cells play a critical role in delayed type hypersensitivity to intact Cryptococcus neoformans.
Authors: Mody C H , Paine R , Jackson C , Chen G H , Toews G B 
Published: December 2022

Abstract
Although cell-mediated immunity is critical for optimal host defense to C. neoformans, the role of T lymphocyte subsets is complex and poorly understood. CD8 cells are important both for optimal host defense against C. neoformans, and for expression of delayed type hypersensitivity (DTH). Because host defense correlates with the ability to mount a DTH response to C. neoformans, the current studies were performed to determine the mechanism by which CD8 cells participate in DTH. Mice were immunized by the intratracheal route with live C. neoformans, or by the subcutaneous route with heat-killed C. neoformans. Mice were depleted of CD8 cells in vivo by administration of mAb. After challenge with soluble cryptococcal Ag, the DTH response was quantified as footpad swelling. We found that mice depleted of CD8 cells before immunization were unable to express DTH. Mice depleted of CD8 cells after immunization but before challenge also were unable to express DTH. Splenocytes of mice depleted of CD8 cells in vivo, before immunization, failed to transfer DTH to naive, undepleted mice. Immune splenocytes depleted of CD8 cells in vitro also failed to transfer DTH to naive, undepleted mice. These data indicate that CD8 cells were necessary during the challenge and immunizing phases of DTH, and were necessary for expression of DTH. However, CD8 cell depletion did not abrogate DTH in mice immunized with either soluble cryptococcal Ag in complete Freund's adjuvant, or sheep red blood cells, which are mediated by CD4 cells. These data suggest that CD8 cells play a critical role in the cell-mediated immune response to C. neoformans. Based on this information, it may be possible to protect hosts with deficiencies of CD4 cells, such as in AIDS, by designing immunizing strategies for stimulating CD8 cells.