Disturbances in peripheral blood B cell subpopulations in autoimmune patients

A variety of cell surface markers are being used to identify B cell subpopulations in peripheral blood. Currently at least eight subpopulations have been identified. Analyses of healthy individuals indicate that in general the various B cell subpopulations exist in relatively similar ratios in unrelated individuals. It has been demonstrated that B lymphocyte homeostasis is disturbed during infection and autoimmune disease. In this review we compare the distribution of B cell subpopulations in the peripheral blood of patients with systemic lupus erythematosus, rheumatoid arthritis and primary Sjogren's syndrome with each other, and with healthy individuals. The different autoimmune diseases have distinct changes in the B cell subpopulations. Understanding the nature of these B subpopulation signatures will potentially impact understanding the mechanisms of disease, diagnosis and therapy

Mechanisms and clinical significance of BIM phosphorylation in chronic lymphocytic leukemia

B-cell receptor and microenvironment-derived signals promote accumulation of chronic lymphocytic leukemia (CLL) cells through increased proliferation and/or decreased apoptosis. In this study, we investigated the regulation of BIM, a proapoptotic BCL2-related protein, which is tightly regulated by phosphorylation. Surface IgM stimulation increased phosphorylation of 2 BIM isoforms, BIMEL and BIML, in a subset of CLL samples. In contrast, in normal B cells, anti-IgM triggered selective phosphorylation of BIMEL only. In CLL, anti-IgM–induced BIM phosphorylation correlated with unmutated IGHV gene status and with progressive disease. Strikingly, it was also associated with progressive disease within the mutated IGHV gene subset. BIM phosphorylation was dependent on MEK1/2 kinase activity, and we identified BIMEL serine 69, previously linked to pro-survival responses, as the major site of phosphorylation in CLL and in Ramos cells. BIMEL/BIML phosphorylation was associated with release of the pro-survival protein MCL1. Coculture of CLL cells with HK cells, a model of the CLL microenvironment, promoted CLL cell survival and was associated with MEK1/2 activation and BIMEL phosphorylation. Hence, BIM phosphorylation appears to play a key role in apoptosis regulation in CLL cells, potentially coordinating antigen and microenvironment-derived survival signals. Antigen-mediated effects on BIM may be an important determinant of clinical behavior. <br/

Development and characterisation of monoclonal antibodies specific for the murine inhibitory Fc gamma RIIB (CD32B)

Tumourgenetics and immunogenetic

Upregulation of FcyRIIb on monocytes is necessary to promote the superagonist activity of TGN1412

The anti-CD28 superagonist antibody TGN1412 caused life-threatening cytokine release syndrome (CRS) in healthy volunteers, which had not been predicted by preclinical testing. T cells in fresh peripheral blood mononuclear cells (PBMCs) do not respond to soluble TGN1412 but do respond following high-density (HD) preculture. We show for the first time that this response is dependent on crystallizable fragment gamma receptor IIb (Fc?RIIb) expression on monocytes. This was unexpected because, unlike B cells, circulating monocytes express little or no Fc?RIIb. However, Fc?RIIb expression is logarithmically increased on monocytes during HD preculture, and this upregulation is necessary and sufficient to explain TGN1412 potency after HD preculture. B-cell Fc?RIIb expression is unchanged by HD preculture, but B cells can support TGN1412-mediated T-cell proliferation when added at a frequency higher than that in PBMCs. Although low-density (LD) precultured PBMCs do not respond to TGN1412, T cells from LD preculture are fully responsive when cocultured with Fc?RIIb-expressing monocytes from HD preculture, which shows that they are fully able to respond to TGN1412-mediated activation. Our novel findings demonstrate that cross-linking by Fc?RIIb is critical for the superagonist activity of TGN1412 after HD preculture, and this may contribute to CRS in humans because of the close association of Fc?RIIb-bearing cells with T cells in lymphoid tissues

Detection of candidate biomarkers of prostate cancer progression in serum; a depletion-free 3D LC/MS quantitative proteomics pilot study

Background: prostate cancer (PCa) is the most common male cancer in the United Kingdom and we aimed to identify clinically relevant biomarkers corresponding to stage progression of the disease.Methods: we used enhanced proteomic profiling of PCa progression using iTRAQ 3D LC mass spectrometry on high-quality serum samples to identify biomarkers of PCa.Results: we identified 41000 proteins. Following specific inclusion/exclusion criteria we targeted seven proteins of which two were validated by ELISA and six potentially interacted forming an ‘interactome’ with only a single protein linking each marker. This network also includes accepted cancer markers, such as TNF, STAT3, NF-kB and IL6.Conclusions: our linked and interrelated biomarker network highlights the potential utility of six of our seven markers as a panel for diagnosing PCa and, critically, in determining the stage of the disease. Our validation analysis of the MS-identified proteins found that SAA alongside KLK3 may improve categorisation of PCa than by KLK3 alone, and that TSR1, although not significant in this model, might also be a clinically relevant biomarker

Isotype switching converts anti-CD40 antagonism to agonism to elicit potent antitumor activity

Anti-CD40 monoclonal antibodies (mAbs) comprise agonists and antagonists, which display promising therapeutic activities in cancer and autoimmunity, respectively. We previously showed that epitope and isotype interact to deliver optimal agonistic anti-CD40 mAbs. The impact of Fc engineering on antagonists, however, remains largely unexplored. Here, we show that clinically relevant antagonists used for treating autoimmune conditions can be converted into potent FcyR-independent agonists with remarkable antitumor activity by isotype switching to hIgG2. One antagonist is converted to a super-agonist with greater potency than previously reported highly agonistic anti-CD40 mAbs. Such conversion is dependent on the unique disulfide bonding properties of the hIgG2 hinge. This investigation highlights the transformative capacity of the hIgG2 isotype for converting antagonists to agonists to treat cancer

Isotype Switching Converts Anti-CD40 Antagonism to Agonism to Elicit Potent Antitumor Activity

Anti-CD40 monoclonal antibodies (mAbs) comprise agonists and antagonists, which display promising therapeutic activities in cancer and autoimmunity, respectively. We previously showed that epitope and isotype interact to deliver optimal agonistic anti-CD40 mAbs. The impact of Fc engineering on antagonists, however, remains largely unexplored. Here, we show that clinically relevant antagonists used for treating autoimmune conditions can be converted into potent FcyR-independent agonists with remarkable antitumor activity by isotype switching to hIgG2. One antagonist is converted to a super-agonist with greater potency than previously reported highly agonistic anti-CD40 mAbs. Such conversion is dependent on the unique disulfide bonding properties of the hIgG2 hinge. This investigation highlights the transformative capacity of the hIgG2 isotype for converting antagonists to agonists to treat cancer.Functional Genomics of Systemic Disorder

Fc gamma receptor IIb on target B cells promotes rituximab internalization and reduces clinical efficacy

The anti-CD20 mAb rituximab is central to the treatment of B-cell malignancies, but resistance remains a significant problem. We recently reported that resistance could be explained, in part, by internalization of rituximab (type I anti-CD20) from the surface of certain B-cell malignancies, thus limiting engagement of natural effectors and increasing mAb consumption. Internalization of rituximab was most evident in chronic lymphocytic leukemia (CLL) and mantle cell lymphoma (MCL), but the extent of internalization was heterogeneous within each disease. Here, we show that the inhibitory Fc?RIIb on target B cells promotes this process and is largely responsible for the observed heterogeneity across a range of B-cell malignancies. Internalization correlated strongly with Fc?RIIb expression on normal and malignant B cells, and resulted in reduced macrophage phagocytosis of mAb-coated targets. Furthermore, transfection of Fc?RIIb into Fc?RIIb negative Ramos cells increased internalization of rituximab in a dose-dependent manner. Target-cell Fc?RIIb promoted rituximab internalization in a cis fashion and was independent of Fc?RIIb on neighboring cells. It became phosphorylated and internalized along with CD20:anti-CD20 complexes before lysosomal degradation. In MCL patients, high Fc?RIIb expression predicted less durable responses after rituximab-containing regimens. Therefore, target-cell Fc?RIIb provides a potential biomarker of response to type I anti-CD20 mA

Empoderamiento de las organizciones: la importancia de conocer su percepcion sobre el entorno economico

Functional Genomics of Systemic Disorder