bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sex hormone and IL-6 regulation of antigen presentation in the female reproductive tract mucosal tissues.
Authors: Prabhala R H , Wira C R 
Published: December 2022

Abstract
The purpose of this study was to determine whether Ag presentation takes place in the female reproductive tract and if the stage of the reproductive cycle, sex hormones, and IL-6 regulate uterine Ag presentation. Purified epithelial and mixed stromal cells were incubated with sensitized lymph node T lymphocytes in the presence of OVA. Ag presentation was highest at proestrus, the stage of the reproductive cycle that immediately precedes ovulation when estradiol levels peak, and lowest at estrus, when sperm enter the uterus in preparation for fertilization. Further, these studies demonstrate that estradiol given to ovariectomized rats increases uterine cell Ag presentation relative to that in controls. In the presence of mouse anti-rat Ia Ab, Ag presentation was blocked, indicating that Ag presentation by uterine cells is MHC class II restricted. In studies to analyze Ag presentation at sites distal to the female reproductive tract, we found that Ag presentation by adherent cells from the spleen is elevated at proestrus relative to that at other stages of the estrous cycle. When IL-6 was placed in the uterine lumen of ovariectomized rats, Ag presentation by epithelial and mixed stromal cells as well as mitogenesis by spleen cells were increased significantly relative to those in controls. These studies demonstrate that the female reproductive tract is an inductive site for immune responses and that mucosal immune protection may be either enhanced or suppressed depending on the endocrine balance when the female reproductive tract is exposed to pathogens.
Suppressor T cell-activating macrophages in ultraviolet-irradiated human skin induce a novel, TGF-beta-dependent form of T cell activation characterized by deficient IL-2r alpha expression.
Authors: Stevens S R , Shibaki A , Meunier L , Cooper K D 
Published: December 2022

Abstract
Because UV-induced epidermal macrophages (UV-Mph) preferentially activate CD4+ T suppressor-inducer cells and induce tolerance, we hypothesized that they differentially up-regulate T cell early activation genes compared with constitutive epidermal APC, Langerhans cells. We used epidermal cells from UV-exposed (UV-EC) and control (C-EC) human skin to stimulate allogeneic CD4+ T lymphocytes. Reverse transcriptase-PCR revealed that both C-EC (Langerhans cells) and UV-EC (UV-Mph) induced 10(3)- to 10(6)-fold increases in IL-2 mRNA. However, while T cells stimulated by C-EC for 48 h showed a greater than 10(3)-fold increase in IL-2R alpha mRNA, those stimulated by UV-EC did not (n = 5, p = 0.004). Flow cytometry demonstrated that 4.1 +/- 2.3% of unstimulated CD4+ lymphocytes expressed cell surface IL-2R alpha, which increased to 15.7 +/- 1.8% upon stimulation by C-EC for 48 h, but stimulation by UV-EC failed to increase the IL-2R alpha+ population (n = 3, p = 0.038). The addition of neutralizing anti-TGF-beta Abs to UV-EC-stimulated cultures restored CD4+ cell surface IL-2R alpha expression to 12.9 +/- 0.2%. CD4+ T cell activation by UV-Mph is distinct from previously described models of tolerance such as Th2 activation (IFN-gamma mRNA was induced and IL-4 mRNA was not) and Th1 anergy (IL-2 mRNA levels induced by UV-EC and C-EC were similar). Furthermore, costimulatory signals were provided by UV-Mph; CTLA4-Ig and LFA-3-Ig fusion proteins and Abs to CD2, LFA-3, LFA-1, and ICAM-1 inhibited UV-Mph-induced T cell proliferation. Thus, the altered immune outcome induced by UV-Mph (tolerization) compared with Langerhans cells (sensitization) is reflected as a novel mechanism of initial CD4+ T cell early activation gene expression characterized by TGF-beta-dependent deficient IL-2R alpha expression.
Durable elimination of high affinity, T cell-dependent antibodies by low molecular weight antigen arrays in vivo.
Authors: Symer D E , Reim J , Dintzis R Z , Voss E W , Dintzis H M 
Published: December 2022

Abstract
Ongoing Ab responses to a T cell-dependent Ag can be suppressed in hyperimmune animals by exogenous, multivalent Ag arrays. The pharmacologic basis for this suppression was studied by varying the molecular mass, ligand valence, and dose of Ag arrays, and then determining their efficacy, pharmacokinetics, and tissue distribution. Arrays ranging in molecular mass from 30 to 500 kDa caused initial clearance of specific serum Abs, but only the smaller arrays caused persistent suppression despite their relatively lower binding avidity and shorter retention in vivo. Suppression by the smaller arrays at lower doses was biphasic, implying two distinct modes of Ab elimination. High affinity IgG was eliminated preferentially, as shown by calibrated variable ligand-density ELISA. Suppressive arrays were localized discretely in the splenic germinal centers of hyperimmune animals. These results indicate that Ag array mass, ligand valence, and dose all play critical roles, and histologic compartmentalization may also be a pertinent parameter, in determining suppressive efficacy in vivo.
Induction of germ-line gamma 1 and epsilon Ig gene expression in murine B cells. IL-4 and the CD40 ligand-CD40 interaction provide distinct but synergistic signals.
Authors: Warren W D , Berton M T 
Published: December 2022

Abstract
The interaction between B cell CD40 and its ligand (CD40L) on activated Th cells provides a critical signal necessary for T cell-dependent isotype switching. Previous studies suggest that this signal might be important in regulating isotype switching at the level of germ-line Ig transcription. To assess the effects of the CD40L-CD40 interaction on germ-line Ig transcript expression in murine B cells, a membrane-bound form of mouse CD40L was expressed in the baculovirus system. We show that stimulation of resting splenic B cells with CD40L-expressing Sf9 cells induces germ-line gamma 1 and epsilon transcripts independently of cytokines. The CD40-mediated induction cannot be blocked by anti-IL-4 Ab and is not mediated by other cytokines secreted endogenously in response to CD40 stimulation. Importantly, stimulation with CD40L and IL-4 together has a significant synergistic effect on germ-line transcript expression. Stimulation of CD40 does not activate the NF-IL-4-gamma 1 DNA binding factor believed to be required for IL-4-dependent germ-line gamma 1 transcription. Moreover, mutation of the NF-IL-4-gamma 1 DNA binding site in a germ-line gamma 1 promoter-luciferase reporter gene construct completely ablates IL-4 responsiveness but has no effect on responsiveness to CD40L in transient transfection assays. These results demonstrate that the CD40L-CD40 interaction and IL-4 activate germ-line Ig gene transcription by distinct but synergistic mechanisms and suggest that multiple signals may be required to induce sufficient germ-line transcription and/or germ-line transcript levels necessary to target switch recombination.
Naturally processed peptides from rheumatoid arthritis associated and non-associated HLA-DR alleles.
Authors: Kirschmann D A , Duffin K L , Smith C E , Welply J K , Howard S C , Schwartz B D , Woulfe S L 
Published: December 2022

Abstract
Naturally processed peptides from immunoaffinity-purified HLA-DRB1*0401, -DRB1*0404 (rheumatoid arthritis (RA)-associated), and -DRB1*0402 (non-RA-associated) molecules were analyzed by capillary liquid chromatography and mass spectrometry. The molecular weights observed for more than 60 eluted peptides from each HLA-DR protein ranged from 788 to 3535 atomic mass units, corresponding to peptides 7 to 32 amino acids in length. Sequencing of more than 60 of the abundant peptides revealed nested sets of peptides that were derived from only 12 different proteins. The majority of these proteins were membrane-associated (HLA class I, class II, and Ig molecules). Synthetic peptides, corresponding to endogenous peptide sequences, bound with high affinity (5 to 80 nM) to the HLA-DR molecules from which they were eluted. In addition, most were promiscuous binding peptides in that they also bound to other HLA-DR molecules. Truncations of eluted peptide sequences and alanine scanning mutational analysis of a Mycobacterium leprae peptide were used to identify the peptide residues involved in binding to DRB1*0404 and DRB1*0402 molecules. Furthermore, an invariant chain peptide was eluted from the DRB1*0402 molecules but not from the RA-associated molecules. The lack of invariant chain peptides from DRB1*0401 and DRB1*0404 molecules may contribute to the loading of autoantigen peptides into these molecules and to their association with disease.
Targeted removal of the mu switch region from mouse hybridoma cells. A test of its role in gene expression in the endogenous IgH locus.
Authors: Oancea A E , Tsui F W , Shulman M J 
Published: December 2022

Abstract
The switch regions adjoining the DNA encoding the Ig heavy chain constant regions have been implicated in gene expression as well as isotype switching, in that transgenic mice express switch-containing transgenes at a level 100- to 1000-fold higher than the corresponding switch-deleted transgenes. To test whether the switch region of the natural IgH locus is also required for high level expression we have used homologous recombination to generate targeted recombinant hybridoma cell lines that lack the switch region sequences from the major intron of the mu gene. The expression pattern of these switch knock-out cell lines was compared with that of the parental cell line as well as to that of control recombinants using both steady-state mRNA level and nuclear run-on activity to assess heavy chain gene expression. In striking contrast with the results reported for transgenic animals, we have found only a minimal effect, if any, of deleting the switch element from the natural chromosomal location.
Endogenous IL-2 contributes to T cell expansion and IFN-gamma production during lymphocytic choriomeningitis virus infection.
Authors: Cousens L P , Orange J S , Biron C A 
Published: December 2022

Abstract
IL-2-deficient mice were used to examine the role of endogenous IL-2 for supporting T cell proliferative responses during infection with lymphocytic choriomeningitis virus (LCMV). The studies showed that, although virus-specific CTL activity was induced in the absence of IL-2, the overall magnitude of the response was profoundly inhibited. Examination of proportions and numbers of CD8+ T cells demonstrated that the normal virus-induced expansion of these cells was virtually eliminated in spleens and dramatically decreased in lymph nodes from IL-2-negative mice. Absence of endogenous IL-2 also significantly inhibited virus-induced activated T cell production of IFN-gamma, as well as increases in frequencies and numbers of IFN-gamma-producing cells. Reductions in immune responses were accompanied by impaired viral clearance. Although T cell responses were dramatically reduced in IL-2-deficient, as compared with IL-2-containing mice, activation signals were being delivered in vivo because induced CTLs were sensitive to the cell cycle-specific toxin, hydroxyurea (HU), and CD8+ T cells had induced expression of the IL-2R alpha- and beta-chains. These studies demonstrated that, although low levels of T cell responses can be induced in the absence of IL-2, the factor plays a unique and critical role in supporting T cell proliferative responses in vivo and in optimizing induction of the biologic functions mediated by these cells. Furthermore, the results identify a role for IL-2 in promoting IFN-gamma production in vivo.
Protective immunity induced by B7/CD28-costimulated gamma delta T cells to the EL-4 lymphoma in allogenic athymic mice.
Authors: Li Y , Newby S A , Johnston J V , Hellström K E , Chen L 
Published: December 2022

Abstract
We previously reported that the murine EL-4 lymphoma (H-2b) transduced with a retrovirus containing the murine B7-1 gene (B7+ EL-4) grew transiently for several weeks and subsequently regressed in allogenic BALB/c (nu/nu) athymic mice (H-2d). We now show that, in contrast, B7+ EL-4 cells grow progressively in several combined immunodeficiency mice, including SCID and NIH III mice, which lack T cells expressing either TCR-alpha beta or -gamma delta. Furthermore, depletion of gamma delta T cells with a specific mAb made possible the progressive growth of B7+ EL-4 cells in 90% of athymic mice while depletion of alpha beta T cells allowed tumor growth in 50% of these mice. Immunization of athymic mice with B7+ EL-4 cells prevented the outgrowth of wild-type B7- EL-4 cells. This protective immunity was abrogated by in vivo treatment with an anti-TCR-gamma delta mAb, further indicating that gamma delta T cells play an important role in tumor rejection by athymic mice. A gamma delta T cell line, Tc1, was established from B7+ EL-4-immunized athymic mice by repeated restimulation in vitro with irradiated B7+ EL-4 cells. When tested against a broad spectrum of target cells, Tc1 lysed several murine lymphoma lines, but did not lyse other tumor lines, suggesting that the Ag recognized by Tc1 has a limited distribution. Our data demonstrate that gamma delta T cells, and, to a less extent, extrathymic alpha beta T cells, mediate an immune response against B7+ EL-4 cells in allogeneic athymic mice.
Inhibition of vaccinia virus DNA replication by inducible expression of nitric oxide synthase.
Authors: Mĕlková Z , Esteban M 
Published: December 2022

Abstract
Nitric oxide (NO) exerts multiple biologic roles in animal cells through differential regulation of three distinct forms of NO synthase encoded by separate genes. Macrophage-inducible nitric oxide synthase (iNOS) has been correlated with inhibition of viral growth, but little is known about the mechanism of this effect. To study the antiviral role of NO, we have generated a vaccinia virus (VV) recombinant expressing iNOS under the control of Escherichia coli LacI operator/repressor elements. When cultured cells of various origins are infected with this recombinant virus, there is inducible expression of iNOS in the presence of isopropylthio-beta-galactoside, as determined by Western blot and by detection of nitrite, a NO oxidation product. The levels of nitrite increase with time after infection, correlating with marked inhibition of VV DNA and late protein synthesis. Expression of VV early proteins is not affected by NO. Inhibition of VV DNA synthesis is likely to be in part a consequence of NO-mediated inhibition of viral ribonucleotide reductase, as this inhibition can be partially overcome by addition of deoxyribonucleosides. Inhibition of the essential viral functions by NO results in a reduction of virus yields by 50 to 90%, depending on the cell line. Thus, our results demonstrate a direct antiviral effect of NO, with inhibition of VV replication occurring at the level of DNA synthesis.
Clearance pathways of soluble immune complexes in the pig. Insights into the adaptive nature of antigen clearance in humans.
Authors: Davies K A , Chapman P T , Norsworthy P J , Jamar F , Athanassiou P , Keelan E T , Harrison A A , Binns R M , Haskard D O , Walport M J 
Published: December 2022

Abstract
Efficient delivery of immune complexes (ICs) to the mononuclear phagocytic system, and subsequent IC processing, may prevent their potentially harmful effects in other tissues and may also be important in the development of humoral immune responses. In mice, rabbits, and primates, the liver and spleen are the main sites of IC clearance. It has been demonstrated previously that the pulmonary capillaries in the pig are lined with macrophages and that certain particulates, including bacteria, localize to this organ. In this study, we used gamma scintigraphy to explore the sites and kinetics of clearance of soluble IC comprising 123I-labeled hepatitis B surface Ag (HBsAg):porcine anti-HBsAg in the Large White pig. At t = 10 min after i.v. injection, 43 +/- 5% (mean +/- SE) IC localized in the lungs, and 36 +/- 6% counts in the liver. At t = 85 min, values were: lungs, 15 +/- 4% and liver, 29 +/- 2%. Findings were similar following intraarterial injection. Complement depletion resulted in more rapid initial IC clearance (t1/2 = 5 min), reduced lung uptake (23 +/- 3% at 10 min), and impaired IC catabolism. In normal animals, 5 to 7% injected IC bound to PBMCs, but no E binding was seen. A fall in PBMC numbers (46 to 59% of baseline), was observed following IC injection. These findings contrast with our previous observations using analogous IC in humans, in which we did not observe any change in peripheral blood leukocyte counts consequent upon complex processing, suggesting that in humans, Es may function as a buffering system for complement-bearing IC in the circulation, preventing their interaction with leukocytes bearing complement and FcR, and the potential activation of these cells.
Collagen-like complement component C1q is a membrane protein of human monocyte-derived macrophages that mediates endocytosis.
Authors: Kaul M , Loos M 
Published: December 2022

Abstract
The collagen-like C1q molecule, a subcomponent of the first component of complement, C1, is synthesized by macrophages (M phi). Previously, we have demonstrated that C1q is a membrane protein of guinea pig peritoneal macrophages (M phi). To extend this observation as a general biologic characteristic of M phi, we investigated human (hu) monocyte-derived M phi. Interestingly, surface labeling with the biotin derivative sulfosuccinimidyl-6-(biotinamido)-hexanoate of M phi, freshly isolated monocytes, lymphocytes, granulocytes, and myelomonocytic U937 cells revealed that C1q occurs only on the surface of M phi and not on the surface of the other cells types. Therefore, C1q appears to be a marker for differentiation into M phi. FITC-labeled, fixed Staphylococcus aureus coupled to membrane C1q via a monoclonal alpha-hu-C1q Ab were used to demonstrate that membrane C1q is capable of mediating phagocytosis. Various detergents (Nonidet P-40, digitonin, lubrol, and Triton X-114) were used to solubilize membrane C1q. Membrane C1q of hu M phi is tightly bound to or located in the intact membrane, since treatment of cells with acidic buffers ("acid strip") failed to remove C1q from the cell surface. However, repeated freezing and thawing of cells and washing of segregated membranes with buffer containing 1 M KCl and 3 M urea brought about a marked release of membrane C1q.
Insertional mutagenesis affecting programmed cell death leads to thymic hyperplasia and altered thymopoiesis.
Authors: Volkmann A , Döffinger R , Rüther U , Kyewski B A 
Published: December 2022

Abstract
The mouse mutant Ft displays thymic hyperplasia and fused toes (Ft) of the forelimbs. Both phenotypic abnormalities are caused by transgene insertion in the D region of chromosome 8. While the forelimb defect is probably caused by developmentally dysregulated programmed cell death, the mechanism underlying thymic hyperplasia has not been characterized. In this work, we show that expansion of the thymocyte compartment progresses with time, is polyclonal, and affects all major thymocyte subsets, including the earliest CD4-8- subset, i.e., CD44+ CD25- cells; hyperplasia is not an autonomous property of mutant T cells, but is caused indirectly by a primary defect in thymic stromal. The rate of cell division and the cell turnover of immature CD4-8- and CD4+8+ thymocytes under steady state conditions are not altered in hyperplastic Ft thymi. Immature CD4+8+ thymocytes of mutant mice, however, are less susceptible to induction in vitro of programmed cell death by different modes (TCR cross-linking, cortisone, or radiation). Increased production of thymocytes results in increased export of T cells, yet the size and composition of the peripheral T cell pool are normal. Overproduction of immature CD4+8+ thymocytes is offset partly by a reduced conversion rate of CD4+8+ double positive to single positive thymocyte growth control by epithelial cells, and may serve as a model to study the regulation of early thymopoiesis.
Stimulus specificity of matrix metalloproteinase dependence of human T cell migration through a model basement membrane.
Authors: Xia M , Leppert D , Hauser S L , Sreedharan S P , Nelson P J , Krensky A M , Goetzl E J 
Published: December 2022

Abstract
Chemotaxis of human T lymphoblastoma cells of the Tsup-1 line, which migrate similarly to blood T cells, through a layer of basement membrane-like Matrigel on a polycarbonate micropore filter was evoked by vasoactive intestinal peptide (VIP; concentration for a maximal response, 10(-7)M), IL-2 (10(-9)M), and the chemokines RANTES (10(-10)M) and macrophage inflammatory protein-1 alpha (10(-10)M). Chemotactic concentrations of each factor increased Tsup-1 cell secretion of matrix metalloproteinase-9 (MMP-9), with significant responses by 4 h for VIP, IL-2, and IL-4, but only after 24 h for macrophage inflammatory protein-1 alpha and RANTES, as quantified by Western blots and zymography. 3H-Labeled type IV human collagen incorporated in the Matrigel layer was degraded by migrating Tsup-1 cells, as assessed by release of radioactive fragments of the collagen. The in situ degradation of type IV collagen in Matrigel by migrating Tsup-1 cells was enhanced most significantly by VIP, IL-2, and IL-4 after 4 h at concentrations that increased the secretion of MMP-9 optimally, but only after 24 h by macrophage inflammatory protein-1 alpha and RANTES. The specific MMP inhibitor GM6001 suppressed Tsup-1 cell MMP activity evoked by all stimuli, as determined by zymography and in situ degradation of 3H-Labeled type IV human collagen. The chemotactic migration of Tsup-1 cells through Matrigel, but not through a filter alone, in response to optimal concentrations of VIP, IL-2, and IL-4, but not the chemokines, was inhibited by GM6001, with a concentration dependence similar to that for suppression of MMP activity. Thus elicitation of T cell chemotactic migration through a model basement membrane by stimuli that increase MMP activity early in the response depends on degradation of matrix proteins by MMP, whereas stimuli that recruit MMP late may rely on early activation of other proteases.
Amino acid residues on the I-Ak alpha-chain required for the binding and stability of two antigenic peptides.
Authors: Nelson C A , Viner N , Young S , Petzold S , Benoist C , Mathis D , Unanue E R 
Published: December 2022

Abstract
The class II molecules of the MHC bind processed Ag fragments (peptides) for presentation to T cells, but the role of individual MHC residues in binding these peptides has not been entirely defined. A panel of 27 mutant I-Ak transfectants was analyzed for the capacity to bind 2 unrelated peptides. The main peptides examined were hen egg lysozyme residues 48-62 and heat shock protein (hsp70) to residues 28-41. Alanine substitutions of sites in the alpha-helical region of the I-Ak alpha-chain altered the ability of this class II protein to bind both peptides. Of the 27 substitutions tested, nine caused a decrease in peptide binding while only three caused an increase in peptide binding. The stabilities of these altered I-Ak-peptide complexes were also examined on SDS-Page. Complexes with lowered stabilities were observed after only four substitutions, and in all four cases this loss of stability was accompanied by a loss in hen egg lysozyme or hsp70 peptide-binding ability. Further, three of these residues lie in the short extended strand at the N terminus of the alpha-helix of the alpha 1 domain, suggesting that this region of I-Ak molecule may be critical for the formation of stable peptide-MHC complexes.