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Isotype switching

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https://www.readbyqxmd.com/read/28095113/quantitative-analysis-of-cell-surface-antigen-antibody-interaction-using-gaussia-princeps-luciferase-antibody-fusion-proteins
#1
Juliane Kums, Johannes Nelke, Benedikt Rüth, Viktoria Schäfer, Daniela Siegmund, Harald Wajant
Cell surface antigen-specific antibodies are of substantial diagnostic and therapeutic importance. The binding properties of such antibodies are usually evaluated by cell-free assays, in particular surface plasmon resonance (SPR) analysis, or flow cytometry. SPR analyses allow the detailed quantitative and dynamic evaluation of the binding properties of antibodies, but need purified, typically recombinantly produced antigens. It can, however, be difficult to produce the required antigen. Furthermore, cellular factors influencing the antigen-antibody interaction are not considered by this method...
January 17, 2017: MAbs
https://www.readbyqxmd.com/read/28093652/structural-basis-for-the-isotype-specific-interactions-of-ferredoxin-and-ferredoxin-nadp-oxidoreductase-an-evolutionary-switch-between-photosynthetic-and-heterotrophic-assimilation
#2
Fumio Shinohara, Genji Kurisu, Guy Hanke, Caroline Bowsher, Toshiharu Hase, Yoko Kimata-Ariga
In higher plants, ferredoxin (Fd) and ferredoxin-NADP(+) reductase (FNR) are each present as distinct isoproteins of photosynthetic type (leaf type) and non-photosynthetic type (root type). Root-type Fd and FNR are considered to facilitate the electron transfer from NADPH to Fd in the direction opposite to that occurring in the photosynthetic processes. We previously reported the crystal structure of the electron transfer complex between maize leaf FNR and Fd (leaf FNR:Fd complex), providing insights into the molecular interactions of the two proteins...
January 16, 2017: Photosynthesis Research
https://www.readbyqxmd.com/read/28086979/b-cell-repertoires-in-hla-sensitized-kidney-transplant-candidates-undergoing-desensitization-therapy
#3
John F Beausang, H Christina Fan, Rene Sit, Maria U Hutchins, Kshama Jirage, Rachael Curtis, Edward Hutchins, Stephen R Quake, Julie M Yabu
BACKGROUND: Kidney transplantation is the most effective treatment for end-stage renal disease. Sensitization refers to pre-existing antibodies against human leukocyte antigen (HLA) protein and remains a major barrier to successful transplantation. Despite implementation of desensitization strategies, many candidates fail to respond. Our objective was to determine whether measuring B cell repertoires could differentiate candidates that respond to desensitization therapy. METHODS: We developed an assay based on high-throughput DNA sequencing of the variable domain of the heavy chain of immunoglobulin genes to measure changes in B cell repertoires in 19 highly HLA-sensitized kidney transplant candidates undergoing desensitization and 7 controls with low to moderate HLA sensitization levels...
January 13, 2017: Journal of Translational Medicine
https://www.readbyqxmd.com/read/28065739/r-loop-depletion-by-over-expressed-rnase-h1-in-mouse-b-cells-increases-activation-induced-deaminase-access-to-the-transcribed-strand-without-altering-frequency-of-isotype-switching
#4
Robert W Maul, Hyongi Chon, Kiran Sakhuja, Susana M Cerritelli, Lina A Gugliotti, Patricia J Gearhart, Robert J Crouch
R-loops, three-strand structures consisting of mRNA hybridized to the complementary DNA and a single-stranded DNA loop, are formed in switch regions on the heavy-chain immunoglobulin locus. To determine if R-loops have a direct effect on any of the steps involved in isotype switching, we generated a transgenic mouse that over-expressed RNase H1, an enzyme that cleaves the RNA of RNA/DNA hybrids in B cells. R-loops in the switch μ region were depleted by 70% in ex vivo activated splenic B cells. Frequencies of isotype switching to IgG1, IgG2b, IgG2c, and IgG3 were the same as C57BL/6 control cells...
January 6, 2017: Journal of Molecular Biology
https://www.readbyqxmd.com/read/28053999/b-cell-populations-discriminate-between-pediatric-and-adult-onset-multiple-sclerosis
#5
Alexander Schwarz, Bettina Balint, Mirjam Korporal-Kuhnke, Sven Jarius, Kathrin von Engelhardt, Alexandra Fürwentsches, Cornelia Bussmann, Friedrich Ebinger, Brigitte Wildemann, Jürgen Haas
OBJECTIVE: To comparatively assess the B-cell composition in blood and CSF of patients with pediatric-onset multiple sclerosis (pedMS) and adult-onset multiple sclerosis (adMS). METHODS: In this cross-sectional study, we obtained blood and CSF samples from 25 patients with pedMS (8-18 years) and 40 patients with adMS (23-65 years) and blood specimens from 66 controls (1-55 years). By using multicolor flow cytometry, we identified naive, transitional, isotype class-switched memory, nonswitched memory, and double-negative memory B-cell subsets as well as plasmablasts (PB) and terminally differentiated plasma cells (PC)...
January 2017: Neurology® Neuroimmunology & Neuroinflammation
https://www.readbyqxmd.com/read/28011866/the-aryl-hydrocarbon-receptor-controls-cell-fate-decisions-in-b-cells
#6
Bharat Vaidyanathan, Ashutosh Chaudhry, William T Yewdell, Davide Angeletti, Wei-Feng Yen, Adam K Wheatley, Christopher A Bradfield, Adrian B McDermott, Jonathan W Yewdell, Alexander Y Rudensky, Jayanta Chaudhuri
Generation of cellular heterogeneity is an essential feature of the adaptive immune system. This is best exemplified during humoral immune response when an expanding B cell clone assumes multiple cell fates, including class-switched B cells, antibody-secreting plasma cells, and memory B cells. Although each cell type is essential for immunity, their generation must be exquisitely controlled because a class-switched B cell cannot revert back to the parent isotype, and a terminally differentiated plasma cell cannot contribute to the memory pool...
January 2017: Journal of Experimental Medicine
https://www.readbyqxmd.com/read/27974207/dna-replication-origins-in-immunoglobulin-switch-regions-regulate-class-switch-recombination-in-an-r-loop-dependent-manner
#7
Eva-Maria Wiedemann, Mihaela Peycheva, Rushad Pavri
Class switch recombination (CSR) at the immunoglobulin heavy chain (IgH) locus generates antibody isotypes. CSR depends on double-strand breaks (DSBs) induced by activation-induced cytidine deaminase (AID). Although DSB formation and repair machineries are active in G1 phase, efficient CSR is dependent on cell proliferation and S phase entry; however, the underlying mechanisms are obscure. Here, we show that efficient CSR requires the replicative helicase, the Mcm complex. Mcm proteins are enriched at IgH switch regions during CSR, leading to assembly of facultative replication origins that require Mcm helicase function for productive CSR...
December 13, 2016: Cell Reports
https://www.readbyqxmd.com/read/27940658/cutting-edge-il-10-is-essential-for-the-generation-of-germinal-center-b-cell-responses-and-anti-plasmodium-humoral-immunity
#8
Jenna J Guthmiller, Amy C Graham, Ryan A Zander, Rosemary L Pope, Noah S Butler
IL-10 is a pleiotropic cytokine expressed during malaria, a disease characterized by short-lived, parasite-specific Ab responses. The role of IL-10 in regulating B cell responses during malaria is not known. In this study we report that IL-10 is essential for anti-Plasmodium humoral immunity. We identify that germinal center (GC) B cell reactions, isotype-switched Ab responses, parasite control, and host survival require B cell-intrinsic IL-10 signaling. IL-10 also indirectly supports humoral immunity by suppressing excessive IFN-γ, which induces T-bet expression in B cells...
January 15, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/27924814/mature-igm-expressing-plasma-cells-sense-antigen-and-develop-competence-for-cytokine-production-upon-antigenic-challenge
#9
Pascal Blanc, Ludovic Moro-Sibilot, Lucas Barthly, Ferdinand Jagot, Sébastien This, Simon de Bernard, Laurent Buffat, Sébastien Dussurgey, Renaud Colisson, Elias Hobeika, Thierry Fest, Morgan Taillardet, Olivier Thaunat, Antoine Sicard, Paul Mondière, Laurent Genestier, Stephen L Nutt, Thierry Defrance
Dogma holds that plasma cells, as opposed to B cells, cannot bind antigen because they have switched from expression of membrane-bound immunoglobulins (Ig) that constitute the B-cell receptor (BCR) to production of the secreted form of immunoglobulins. Here we compare the phenotypical and functional attributes of plasma cells generated by the T-cell-dependent and T-cell-independent forms of the hapten NP. We show that the nature of the secreted Ig isotype, rather than the chemical structure of the immunizing antigen, defines two functionally distinct populations of plasma cells...
December 7, 2016: Nature Communications
https://www.readbyqxmd.com/read/27919754/neutralization-takes-precedence-over-igg-or-iga-isotype-related-functions-in-mucosal-hiv-1-antibody-mediated-protection
#10
Rena D Astronomo, Sampa Santra, Lamar Ballweber-Fleming, Katharine G Westerberg, Linh Mach, Tiffany Hensley-McBain, Laura Sutherland, Benjamin Mildenberg, Georgeanna Morton, Nicole L Yates, Gregory J Mize, Justin Pollara, Florian Hladik, Christina Ochsenbauer, Thomas N Denny, Ranjit Warrier, Supachai Rerks-Ngarm, Punnee Pitisuttithum, Sorachai Nitayapan, Jaranit Kaewkungwal, Guido Ferrari, George M Shaw, Shi-Mao Xia, Hua-Xin Liao, David C Montefiori, Georgia D Tomaras, Barton F Haynes, M Juliana McElrath
HIV-1 infection occurs primarily through mucosal transmission. Application of biologically relevant mucosal models can advance understanding of the functional properties of antibodies that mediate HIV protection, thereby guiding antibody-based vaccine development. Here, we employed a human ex vivo vaginal HIV-1 infection model and a rhesus macaque in vivo intrarectal SHIV challenge model to probe the protective capacity of monoclonal broadly-neutralizing (bnAb) and non-neutralizing Abs (nnAbs) that were functionally modified by isotype switching...
December 2016: EBioMedicine
https://www.readbyqxmd.com/read/27897229/global-gene-regulation-during-activation-of-immunoglobulin-class-switching-in-human-b-cells
#11
Youming Zhang, David J Fear, Saffron A G Willis-Owen, William O Cookson, Miriam F Moffatt
Immunoglobulin class switch recombination (CSR) to IgE is a tightly regulated process central to atopic disease. To profile the B-cell transcriptional responses underlying the activation of the germinal centre activities leading to the generation of IgE, naïve human B-cells were stimulated with IL-4 and anti-CD40. Gene expression and alternative splicing were profiled over 12 days using the Affymetrix Human Exon 1.0 ST Array. A total of 1,399 genes, forming 13 temporal profiles were differentially expressed...
November 29, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27881702/roles-of-aluminum-hydroxide-and-monophosphoryl-lipid-a-adjuvants-in-overcoming-cd4-t-cell-deficiency-to-induce-isotype-switched-igg-antibody-responses-and-protection-by-t-dependent-influenza-vaccine
#12
Eun-Ju Ko, Young-Tae Lee, Ki-Hye Kim, Youri Lee, Yu-Jin Jung, Min-Chul Kim, Yu-Na Lee, Taeuk Kang, Sang-Moo Kang
Vaccine adjuvant effects in the CD4-deficient condition largely remain unknown. We investigated the roles of combined monophosphoryl lipid A (MPL) and aluminum hydroxide (Alum) adjuvant (MPL+Alum) in inducing immunity after immunization of CD4 knockout (CD4KO) and wild-type (WT) mice with T-dependent influenza vaccine. MPL+Alum adjuvant mediated IgG isotype-switched Abs, IgG-secreting cell responses, and protection in CD4KO mice, which were comparable to those in WT mice. In contrast, Alum adjuvant effects were dependent on CD4(+) T cells...
January 1, 2017: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/27880772/t-cell-production-of-ifn%C3%AE-in-response-to-tlr7-il-12-stimulates-optimal-b-cell-responses-to-viruses
#13
Kira Rubtsova, Anatoly V Rubtsov, Kalani Halemano, Sam X Li, John W Kappler, Mario L Santiago, Philippa Marrack
Knowledge of the processes that underlie IgG subclass switching could inform strategies designed to counteract infections and autoimmunity. Here we show that TLR7 ligands induce subsets of memory CD4 and CD8 T cells to secrete interferon γ (IFNγ) in the absence of antigen receptor stimulation. In turn, TLR ligation and IFNγ cause B cells to express the transcription factor, T-bet, and to switch immunoglobulin production to IgG2a/c. Absence of TLR7 in T cells leads to the impaired T-bet expression in B cells and subsequent inefficient IgG2a isotype switching both in vitro and during the infection with Friend virus in vivo...
2016: PloS One
https://www.readbyqxmd.com/read/27878102/antiretroviral-naive-and-treated-patients-discrepancies-of-b-cell-subsets-during-the-natural-course-of-human-immunodeficiency-virus-type-1-infection
#14
Olga Tsachouridou, Lemonia Skoura, Pantelis Zebekakis, Apostolia Margariti, Adamantini Georgiou, Dimitrios Bougiouklis, Dimitrios Pilalas, Antonios Galanos, Michael Daniilidis, Symeon Metallidis
AIM: To evaluate alterations of memory B cell subpopulations during a 48-wk period in human immunodeficiency virus type 1 (HIV-1) patients. METHODS: Forty-one antiretroviral naïve and 41 treated HIV-1 patients matched for age and duration of HIV infection were recruited. All clinical, epidemiological and laboratory data were recorded or measured. The different B cell subsets were characterized according to their surface markers: Total B cells (CD19(+)), memory B cells (CD19(+)CD27(+), BMCs), resting BMCs (CD19(+)CD27(+)CD21(high), RM), exhausted BMCs (CD19(+)CD21(low)CD27(-), EM), IgM memory B (CD19(+)CD27(+)IgM(high)), isotype-switched BMCs (CD19(+)CD27(+)IgM(-), ITS) and activated BMCs (CD19(+)CD21(low+)CD27(+), AM) at baseline on week 4 and week 48...
November 12, 2016: World Journal of Virology
https://www.readbyqxmd.com/read/27861512/a-rapid-response-humoral-vaccine-platform-exploiting-pre-existing-non-cognate-populations-of-anti-vaccine-or-anti-viral-cd4-t-helper-cells-to-confirm-b-cell-activation
#15
Thomas Hills, Phillip G Jakeman, Robert C Carlisle, Paul Klenerman, Leonard W Seymour, Ryan Cawood
The need for CD4+ T cell responses to arise de novo following vaccination can limit the speed of B cell responses. Populations of pre-existing vaccine-induced or anti-viral CD4+ T cells recognising distinct antigens could be exploited to overcome this limitation. We hypothesise that liposomal vaccine particles encapsulating epitopes that are recognised, after processing and B cell MHCII presentation, by pre-existing CD4+ T cells will exploit this pre-existing T cell help and result in improved antibody responses to distinct target antigens displayed on the particle surface...
2016: PloS One
https://www.readbyqxmd.com/read/27833954/the-role-of-autoantibodies-in-health-and-disease
#16
Isabela Siloşi, Cristian Adrian Siloşi, Mihail Virgil Boldeanu, Manole Cojocaru, Viorel Biciuşcă, Carmen Silvia Avrămescu, Inimioara Mihaela Cojocaru, Maria Bogdan, Roxana Mihaela FolcuŢi
Serum of healthy individuals contains antibodies that react with self and non-self antigens, generated in absence of external antigen stimulation. These antibodies, called natural antibodies, are particularly IgM isotype, are considered natural autoantibodies (NAA), displaying a moderate affinity for self-antigens. Although incidence of NAA in healthy individuals is not reported, it is established that autoreactive antibodies and B-cells, as well as autoreactive T-cells, are present in healthy persons. The functional abilities of NAA are not clear but is well accepted that they may participate in a variety of activities, such as maintenance of immune homeostasis, regulation of the immune response, resistance to infections, transport and functional modulation of biologically active molecules...
2016: Romanian Journal of Morphology and Embryology, Revue Roumaine de Morphologie et Embryologie
https://www.readbyqxmd.com/read/27815447/efficient-culture-of-human-naive-and-memory-b-cells-for-use-as-apcs
#17
Kuei-Ying Su, Akiko Watanabe, Chen-Hao Yeh, Garnett Kelsoe, Masayuki Kuraoka
The ability to culture and expand B cells in vitro has become a useful tool for studying human immunity. A limitation of current methods for human B cell culture is the capacity to support mature B cell proliferation. We developed a culture method to support the efficient activation and proliferation of naive and memory human B cells. This culture supports extensive B cell proliferation, with ∼10(3)-fold increases following 8 d in culture and 10(6)-fold increases when cultures are split and cultured for 8 more days...
November 15, 2016: Journal of Immunology: Official Journal of the American Association of Immunologists
https://www.readbyqxmd.com/read/27799928/evaluation-of-the-antigen-experienced-b-cell-receptor-repertoire-in-healthy-children-and-adults
#18
Hanna IJspeert, Pauline A van Schouwenburg, David van Zessen, Ingrid Pico-Knijnenburg, Gertjan J Driessen, Andrew P Stubbs, Mirjam van der Burg
Upon antigen recognition via their B cell receptor (BR), B cells migrate to the germinal center where they undergo somatic hypermutation (SHM) to increase their affinity for the antigen, and class switch recombination (CSR) to change the effector function of the secreted antibodies. These steps are essential to create an antigen-experienced BR repertoire that efficiently protects the body against pathogens. At the same time, the BR repertoire should be selected to protect against responses to self-antigen or harmless antigens...
2016: Frontiers in Immunology
https://www.readbyqxmd.com/read/27780620/variations-of-b-cell-subpopulations-in-peripheral-blood-of-healthy-mexican-population-according-to-age-relevance-for-diagnosis-of-primary-immunodeficiencies
#19
L Berrón-Ruíz, G López-Herrera, C E Ávalos-Martínez, C Valenzuela-Ponce, E Ramírez-SanJuan, G Santoyo-Sánchez, F Mújica Guzmán, F J Espinosa-Rosales, L Santos-Argumedo
BACKGROUND: Peripheral blood B cells include lymphocytes at various stages of differentiation, each with a specific function in the immune response. All these stages show variations in percentage and absolute number throughout human life. The numbers and proportions of B subpopulation are influenced by factors such as gender, age, ethnicity, and lifestyle. This study establishes reference values according to age of peripheral blood B cell subtypes in healthy Mexican population. METHODS: Peripheral blood from healthy new-borns and adults were analysed for total B cell subpopulations, using surface markers such as CD19, IgM, IgD, CD21, CD24, CD27, and CD38, to identify naïve, memory with and without isotype switch, double-negative, transitional, and plasmablast cells...
November 2016: Allergologia et Immunopathologia
https://www.readbyqxmd.com/read/27764122/blood-plasma-derived-anti-glycan-antibodies-to-sialylated-and-sulfated-glycans-identify-ovarian-cancer-patients
#20
Tatiana Pochechueva, Alexander Chinarev, Andreas Schoetzau, André Fedier, Nicolai V Bovin, Neville F Hacker, Francis Jacob, Viola Heinzelmann-Schwarz
Altered levels of naturally occurring anti-glycan antibodies (AGA) circulating in human blood plasma are found in different pathologies including cancer. Here the levels of AGA directed against 22 negatively charged (sialylated and sulfated) glycans were assessed in high-grade serous ovarian cancer (HGSOC, n = 22) patients and benign controls (n = 31) using our previously developed suspension glycan array (SGA). Specifically, the ability of AGA to differentiate between controls and HGSOC, the most common and aggressive type of ovarian cancer with a poor outcome was determined...
2016: PloS One
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