Transitional B Cells and TLR9 Responses Are Defective in Selective IgA Deficiency.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked FilesSelective IgA deficiency (IgAD) is the most common primary antibody deficiency in the western world with affected individuals suffering from an increased burden of autoimmunity, atopic diseases and infections. It has been shown that IgAD B cells can be induced with germinal center mimicking reactions to produce IgA. However, IgA is the most prevalent antibody in mucosal sites, where antigen-independent responses are important. Much interest has recently focused on the role of TLR9 in both naïve and mature B cell differentiation into IgA secreting plasma cells. Here, we analyze the phenotype and function of T and B cells in individuals with IgAD following IgA-inducing CpG-TLR9 stimulations. The IgAD individuals had significantly lower numbers of transitional B cells (CD19+CD24hiCD38hi) and class-switched memory B cells (CD20+CD27+IgD-) ex vivo. However, proportions of T cell populations ex vivo as well as in vitro induced T effector cells and T regulatory cells were comparable to healthy controls. After CpG stimulation, the transitional B cell defect was further enhanced, especially within its B regulatory subset expressing IL-10. Finally, CpG stimulation failed to induce IgA production in IgAD individuals. Collectively, our results demonstrate a defect of the TLR9 responses in IgAD that leads to B cell dysregulation and decreased IgA production.Icelandic Research Fund University hospital of Iceland research fun

Mapping of Signaling Pathways Linked to sIgAD Reveals Impaired IL-21 Driven STAT3 B-Cell Activation.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked DownloadObjectives: It has recently been shown that individuals with selective IgA deficiency (sIgAD) have defective B cell responses both to T cell dependent and independent mimicking stimulations. The complex intracellular signaling pathways from different stimuli leading to IgA isotype switching have not been fully elucidated. Thus, the main objective of this study was to delineate these pathways and their potential role in the immunopathology linked to sIgAD. Materials and Methods: PBMCs from 10 individuals with sIgAD and 10 healthy controls (HC) were activated in vitro via either a T cell dependent or independent mimicking stimulation. Intracellular phosphorylation of pSTAT3, pSTAT5, pSTAT6, and as pERK1/2 was evaluated in T and B cells using phosphoflow cytometry. Results: By evaluating T cell dependent cytokine driven pathways linked to IgA isotype induction we identified a defect involving an IL-21 driven STAT3 activation isolated to B cells in sIgAD individuals. However, all other signaling pathways studied were found to be normal compared to HC. In T cell dependent cytokine driven stimulations linked to IgA isotype induction the following patterns emerged: (i) IL-10 led to significant STAT3 activation in both T- and B cells; (ii) IL-4 stimulation was predominantly confined to STAT6 activation in both T- and B cells, with some effects on STAT3 activation in T-cells; (iii) as expected, of tested stimuli, IL-2 alone activated STAT5 and some STAT3 activation though in both cases only in T-cells; (iv) IL-21 induced significant activation of STAT3 in both T- and B cells, with some effects on STAT5 activation in T-cells; and finally (v) synergistic effects were noted of IL-4+IL-10 on STAT5 activation in T-cells, and possibly STAT6 in both T- and B cells. On the other hand, CPG induced T cell independent activation was confined to ERK1/2 activation in B cells. Conclusion: Our results indicate a diminished STAT3 phosphorylation following IL-21 stimulation solely in B cells from sIgAD individuals. This can represent aberrant germinal center reactions or developmental halt. Thus, our work provides further insight into the unraveling of the previously hypothesized role of IL-21 to reconstitute immunoglobulin production in primary antibody deficiencies.Icelandic Research Fund University hospital of Iceland research fun

A prominent lack of IgG1-Fc fucosylation of platelet alloantibodies in pregnancy.

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access.Immunoglobulin G (IgG) formed during pregnancy against human platelet antigens (HPAs) of the fetus mediates fetal or neonatal alloimmune thrombocytopenia (FNAIT). Because antibody titer or isotype does not strictly correlate with disease severity, we investigated by mass spectrometry variations in the glycosylation at Asn297 in the IgG Fc because the composition of this glycan can be highly variable, affecting binding to phagocyte IgG-Fc receptors (FcγR). We found markedly decreased levels of core fucosylation of anti-HPA-1a-specific IgG1 from FNAIT patients (n = 48), but not in total serum IgG1. Antibodies with a low amount of fucose displayed higher binding affinity to FcγRIIIa and FcγRIIIb, but not to FcγRIIa, compared with antibodies with a high amount of Fc fucose. Consequently, these antibodies with a low amount of Fc fucose showed enhanced phagocytosis of platelets using FcγRIIIb(+) polymorphonuclear cells or FcγRIIIa(+) monocytes as effector cells, but not with FcγRIIIa(-) monocytes. In addition, the degree of anti-HPA-1a fucosylation correlated positively with the neonatal platelet counts in FNAIT, and negatively to the clinical disease severity. In contrast to the FNAIT patients, no changes in core fucosylation were observed for anti-HLA antibodies in refractory thrombocytopenia (post platelet transfusion), indicating that the level of fucosylation may be antigen dependent and/or related to the immune milieu defined by pregnancy.Sanquin/PPOC-09- 025 Landsteiner Foundation for Blood Transfusion/0721 info:eu-repo/grantAgreement/EC/FP7/27853

Familial predisposition to monoclonal gammopathy of unknown significance, Waldenström's macroglobulinemia, and multiple myeloma

To access publisher full text version of this article. Please click on the hyperlink in Additional Links fieldThe medical literature contains reports of around 130 families with two or more cases of MM, MGUS, or WM. An Icelandic family with multiple cases of MGUS, WM, and lymphoma was first described in 1978. In vitro testing of peripheral blood lymphocytes revealed increased production of immunoglobulins in response to poke-weed mitogen in 10 out of 35 family members, referred to as hyperresponders (HR). Enhanced B-cell survival after stimulation was associated with prolonged expression of Bcl-2. A population-based cancer registry study of 218 MM patients identified 7 additional families. Nine new cases of monoclonal gammopathy were detected by the screening of 350 family members. Further testing confirmed previously identified HR in the originally described family as well as detecting new cases. Only two HR were found in the recently identified families. The long-term aim is to identify the genetic background(s) and biology predisposing to the emergence of a persistent clone of immunoglobulin-producing cells

Sono Osato (far right) as a Maiden, and artists of the company, in Protée, The Original Ballet Russe, Australian tour, His Majesty's Theatre, Melbourne, April 1940 (1) [picture] /

From: Protée : choreographic tableau / by David Lichine and Henry Clifford ; music by Claude Debussy from Danses sacree et profane.; Inscription: "3W/3 (10)".; Part of the collection: Hugh P. Hall collection of photographs, 1938-1940.; Choreography by Michel Fokine ; scenery and costumes by Giorgio de Chirico ; costumes executed by B. Karinska ; scenery executed by Prince A. Schervachidze.; Also available in an electronic version via the internet at: http://nla.gov.au/nla.pic-vn4194073. One of a collection of photographs taken by Hugh P. Hall of 28 ballet productions performed by the Covent Garden Russian Ballet (toured Australia 1938-1939) and the Original Ballet Russe (toured Australia 1939-1940). These are the second and third of the three Ballets Russes companies which toured Australasia between 1936 and 1940. The photographs were taken from the auditorium during a live performance in His Majesty's Theatre, Melbourne and mounted on cardboard for display purposes. For conservation and storage, the photographs have been demounted. The original arrangement of the photographs has been recorded, and details are available from the Pictures Branch of the National Library

Data from: On the perplexingly low rate of transport of IgG2 across the human placenta

The neonatal receptor, FcRn, mediates both serum half–life extension as well as active transport of maternal IgG to the fetus during pregnancy. Therefore, transport efficiency and half-life go hand-in-hand. However, while the half-life of the human IgG2 subclass is comparable to IgG1, the placental transport of IgG2 is not, with the neonatal IgG1 levels generally exceeding maternal levels at birth, but not for IgG2. We hypothesized that the unique short-hinged structure of IgG2, which enables its κ-, but not λ-isotype to form at least three different structural isoforms, might be a contributing factor to these differences. To investigate whether there was any preference for either light chain, we measured placental transport of IgG subclasses as well as κ/λ-light chain isotypes of IgG1 and IgG2 in 27 matched mother-child pairs. We also studied the half-life of IgG1 and IgG2 light chain isotypes in mice, as well as that of synthesized IgG2 structural isotypes κA and κB. In order to investigate serum clearance of IgG1 and IgG2 light-chain isotypes in humans, we quantified the relative proportions of IgG1 and IgG2 light chains in hypogammaglobulinemia patients four weeks after IVIg infusion and compared to the original IVIg isotype composition. None of our results indicate any light chain preference in either of the FcRn mediated mechanisms; half-life extension or maternal transport

Generation of human IgG1 and IgG3 TA99 mAb with histidine-arginine rearrangements in Fc domains at amino acid position 435.

<p>Human IgG1 was mutated to contain an arginine at position 435 (IgG1 H435R), whereas the arginine at position 435 in human IgG3 was changed to histidine (IgG3 R435H). (<b>A</b>) Specific anti-human IgG1 or (<b>B</b>) anti-human IgG3 ELISA confirmed the correct isotype of mAbs. Staining of B16F10-gp75 with (<b>C</b>) different human TA99 mAb and (<b>D</b>) mouse TA99 IgG2a confirmed binding to surface gp75 and equal binding efficiency to gp75 of all human TA99 mAb. Concentration curves of human IgG1 and IgG3 mAb (<b>E</b>) and mouse IgG2a TA99 (<b>F</b>) on B16F10-gp75. Of note, scales of human (<b>E</b>) and mouse (<b>F</b>) antibodies are different.</p

Cytotoxicity assays using murine macrophages and B16F10-gp75 tumour cells.

<p>(<b>A</b>) Remaining B16F10-gp75 cells after a 24 hour incubation with macrophages and 2 μg/ml TA99 mAbs (different isotypes). (<b>B</b>) FACS analysis of co-cultures of DiO labelled murine macrophages (FL1) and DiI labelled B16F10-gp75 (FL2) tumour cells after 24 hours of treatment with 1 μg/ml mouse IgG2a or human IgG1 or IgG3 TA99 mAb. Macrophages, which have phagocytosed B16F10-gp75 tumour cells are encircled in FACS plots. (<b>C</b>) Percentage of remaining viable tumour cells and (<b>D</b>) increase in number of macrophages, which have phagocytosed B16F10-gp75 tumour cells after treatment of co-cultures with different concentrations of mAb. Percentages of tumour cells after culture with isotype antibodies were set at 100%. Double-positive macrophages were depicted relative to the co-cultures with isotype antibodies (set to 1), as described previously [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0177736#pone.0177736.ref004" target="_blank">4</a>]. Mouse MG4 or human HEPC mAb were used as isotypes controls, which were set to 100%. *P<0.05, **P<0.01, ***p<0.001, ****p<0.0001.</p

Data behind all figures.

This file contains all data points for all figures in the associated PLOS ONE manuscrip