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- Bergh, Ann-Charlotte, et al.
(author)
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Silenced B-cell receptor response to autoantigen in a poor-prognostic subset of chronic lymphocytic leukemia
- 2014
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In: Haematologica. - : Ferrata Storti Foundation. - 0390-6078 .- 1592-8721. ; 99:11, s. 1722-1730
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Journal article (peer-reviewed)abstract
- Chronic lymphocytic leukemia B-cells express auto/xeno-antigen-reactive antibodies that bind to self-epitopes and resemble natural IgM antibodies in their repertoire. One of the antigenic structures recognized is oxidation-induced malonedialdehyde present on low-density lipoprotein, apoptotic blebs, and on certain microbes. The poor-prognostic stereotyped subset #1 (Clan I IGHV genes-IGKV1(D)-39) express IgM B-cell receptors that bind oxidized low-density lipoprotein. In this study, we have used for the first time this authentic cognate antigen, since it is more faithful to B-cell physiology than anti-IgM, for analysis of downstream B-cell receptor-signal transduction events. Multivalent oxidized low-density lipoprotein showed specific binding to subset #1 IgM/IgD B-cell receptors, whereas native low-density lipoprotein did not. The antigen-binding induced prompt receptor-clustering, followed by internalization. However, the receptor-signal transduction was silenced, revealing no Ca2+ mobilization or cell-cycle entry, while phosphorylated extracellular-regulated kinase1/2 basal levels were high and could not be elevated further by oxidized low-density lipoprotein. Interestingly, B-cell receptor responsiveness was recovered after 48 hours culture in the absence of antigen in half of the cases. Toll-like receptor 9-ligand was found to breach the B-cell receptor-signaling incompetence in 5 of 12 cases pointing to intra-subset heterogeneity. Altogether, this study supports B-cell receptor-unresponsiveness to cognate self-antigen on its own in poor-prognostic subset #1 chronic lymphocytic leukemia indicating that these cells proliferate by other mechanisms that may override B-cell receptor-silencing brought about in a context of self-tolerance/anergy. These novel findings have implications for the understanding of chronic lymphocytic leukemia pathobiology and therapy.
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| 2. |
- Szymanowski, Aleksander, et al.
(author)
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Soluble Fas ligand is associated with natural killer cell dynamics in coronary artery disease
- 2014
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In: Atherosclerosis. - : Elsevier. - 0021-9150 .- 1879-1484. ; 233:2, s. 616-622
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Journal article (peer-reviewed)abstract
- Objective: Apoptosis of natural killer (NK) cells is increased in patients with coronary artery disease (CAD) and may explain why NK cell levels are altered in these patients. Soluble forms of Fas and Fas ligand (L) are considered as markers of apoptosis. Here, we investigated whether plasma levels of Fas and FasL were associated with NK cell apoptosis and NK cell levels in CAD patients. Methods: Fas and FasL in plasma were determined by ELISA in 2 cohorts of CAD patients; one longitudinal study measuring circulating NK cells and apoptotic NK cells by flow cytometry 1 day, 3 months and 12 months after a coronary event and one cross-sectional study measuring NK cell apoptosis ex vivo. Both studies included matched healthy controls. Fas and FasL were also determined in supernatants from NK cells undergoing cytokine-induced apoptosis in cell culture. Results: In the 12-month longitudinal study, plasma FasL increased by 15% (p less than 0.001) and NK cell levels by 31% (p less than 0.05) while plasma Fas did not change. Plasma FasL and NK cell levels were significantly related at 3 months and 12 months, r = 0.40, p less than 0.01. Furthermore, plasma FasL, but not plasma Fas, correlated with NK cell apoptosis ex vivo in CAD patients, r = 0.54, p less than 0.05. In vitro, cytokine-induced apoptosis of NK cells resulted in abundant release of FasL. Conclusion: In CAD patients, FasL in plasma is associated with both apoptotic susceptibility of NK cells and dynamic changes in circulating NK cells. NK cells are also themselves a potential source of soluble FasL. Our findings link NK cell status to a soluble marker with possible atheroprotective effects thereby supporting a beneficial role of NK cells in CAD.
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