Anti-β2 glycoprotein I (β2GPI) autoantibodies recognize an epitope on the first domain of β2GPI

Anticardiolipin (aCL) autoantibodies are associated with thrombosis, recurrent fetal loss, and thrombocytopenia. Only aCL found in autoimmune disease require the participation of the phospholipid binding plasma protein β2 glycoprotein I (β2GPI) for antibody binding and now are called anti-β2GPI. The antigenic specificity of aCL affinity purified from 11 patients with high titers was evaluated in an effort to better understand the pathophysiology associated with aCL. Seven different recombinant domain-deleted mutants of human β2GPI, and full length human β2GPI (wild-type), were used in competition assays to inhibit the autoantibodies from binding to immobilized wild-type β2GPI. Only those domain-deleted mutants that contained domain 1 inhibited the binding to immobilized wild-type β2GPI from all of the patients. The domain-deleted mutants that contained domain 1 inhibited all aCL in a similar but not identical pattern, suggesting that these aCL recognize a similar, but distinguishable, epitope(s) present on domain 1.

The role of MHC class I glycoproteins in the regulation of induction of cell death in immunocytes by malignant melanoma cells

A deranged expression of MHC class I glycoproteins, characteristic of a variety of malignancies, contributes to the ability of cancer to avoid destruction by T cell-mediated immunity. An abrogation of the metastatic capacity of B16 melanoma cells has been achieved by transfecting an MHC class I-encoding vector into class I-deficient B16 melanoma clones [Gorelik, E., Kim, M., Duty, L. & Galili, U. (1993) Clin. Exp. Metastasis 11, 439–452]. We report here that the deranged expression of class I molecules by B16 melanoma cells is more than a mere acquisition of the capacity to escape immune recognition. Namely, cells of the B16 melanoma prompted splenic lymphocytes to commit death after coculture. However, a class I-expressing and nonmetastatic CL8-2 clone was found to be less potent as an inducer of apoptosis than class I-deficient and metastatic BL9 and BL12 clones. Both Thy1.2+ and Thy1.2− splenocytes underwent cell death when exposed to the class I-deficient BL9 clone. A proportion of CD4+ and CD8+ cells among splenocytes exposed to the BL9 clone was lower than that observed in a coculture with cells of the CL8-2 clone. Consistently, none of the melanoma clones studied produced a ligand to the FAS receptor (FAS-L). Thus, our results provide evidence that (i) the production of FAS-L may not be the sole mechanism by which malignant cells induce apoptosis in immunocytes, and (ii) absence of MHC class I glycoproteins plays an important role in preventing the elimination of potential effector immunocytes by tumor cells.

Dynamic properties of the Ras switch I region and its importance for binding to effectors

We have investigated the dynamic properties of the switch I region of the GTP-binding protein Ras by using mutants of Thr-35, an invariant residue necessary for the switch function. Here we show that these mutants, previously used as partial loss-of-function mutations in cell-based assays, have a reduced affinity to Ras effector proteins without Thr-35 being involved in any interaction. The structure of Ras(T35S)⋅GppNHp was determined by x-ray crystallography. Whereas the overall structure is very similar to wildtype, residues from switch I are completely invisible, indicating that the effector loop region is highly mobile. 31P-NMR data had indicated an equilibrium between two rapidly interconverting conformations, one of which (state 2) corresponds to the structure found in the complex with the effectors. 31P-NMR spectra of Ras mutants (T35S) and (T35A) in the GppNHp form show that the equilibrium is shifted such that they occur predominantly in the nonbinding conformation (state 1). On addition of Ras effectors, Ras(T35S) but not Ras(T35A) shift to positions corresponding to the binding conformation. The structural data were correlated with kinetic experiments that show two-step binding reaction of wild-type and (T35S)Ras with effectors requires the existence of a rate-limiting isomerization step, which is not observed with T35A. The results indicate that minor changes in the switch region, such as removing the side chain methyl group of Thr-35, drastically affect dynamic behavior and, in turn, interaction with effectors. The dynamics of the switch I region appear to be responsible for the conservation of this threonine residue in GTP-binding proteins.

Antiviral activities of the soluble extracellular domains of type I interferon receptors

Alternative splicing leads to the expression of multiple isoforms of the subunits (IFNAR1 and IFNAR2) of the type I IFN receptor. Here we describe two transcripts representing extracellular forms of ovine IFNAR1 and show that soluble extracellular forms of both IFNAR2 and IFNAR1, prepared in recombinant form in Escherichia coli, have antiviral (AV) activity in the absence of IFN. Exposure of Madin-Darby bovine kidney cells to the extracellular domain (R2E) of IFNAR2 at concentrations as low as 10 nM afforded complete protection against vesicular stomatitis virus and led to the rapid activation of the transcription factors ISGF3 and GAF. Although R2E can bind IFN (Kd ≈70 nM), activity was observed irrespective of whether or not ligand was present. R2E was inactive on mouse L929 cells but active on L929 cells expressing a membraneanchored, ovine/human chimeric IFNAR2 with an ovine extracellular domain. The data suggest that AV activity is conferred by the ability of soluble R2E to associate with the transfected IFNAR2 subunit rather than resident murine IFNAR1. Soluble extracellular forms of IFNAR1 have lower AV activity than R2E on Madin-Darby bovine kidney cells but are less species-specific and protect wild-type L929 cells as efficiently as the transfected cell line, presumably by interacting with one of the murine receptor subunits.

Results of a phase-I/II randomized, masked, placebo-controlled trial of recombinant human interleukin-11 (rhIL-11) in the treatment of subjects with active rheumatoid arthritis

Interleukin-11 (IL-11) is a pleiotropic cytokine that regulates the growth and development of hematopoietic stem cells and decreases the proinflammatory mediators of cytokine and nitric oxide production. In animal models of arthritis, treatment with recombinant human IL-11 (rhIL-11) reduces both the level of synovitis and the histologic lesion scores in the joints.

British Balance of Competence Reviews, Part I: ‘Competences about right, so far’. EPIN Working Paper No. 35, October 2013

The first in a series for a CEPS-EPIN project entitled “The British Question and the Search for a Fresh European Narrative” this paper is pegged on an ambitious ongoing exercise by the British government to review all the competences of the European Union. The intention is that this should provide a basis for informed debate before the referendum on the UK remaining in the EU or not, which is scheduled for 2017. This paper summarises the first six reviews, each of which runs to around 80 pages, covering foreign policy, development policy, taxation, the single market, food safety, and public health. The present authors then add their own assessments of these materials. While understandably giving due place to British interests, they are of general European relevance. The substantive conclusions of this first set of reviews are that the competences of the EU are judged by respondents to be ‘about right’ on the whole, which came as a surprise to eurosceptic MPs and the tabloid media. Our own view is that the reviews are objective and impressively researched, and these populist complaints are illustrating the huge gap between the views of informed stakeholders and general public opinion, and therefore also the hazard of subjecting the ‘in or out’ choice for decision by referendum. If the referendum is to endorse the UK’s continuing membership there will have to emerge some fresh popular narratives about the EU. The paper therefore concludes with some thoughts along these lines, both for the UK and the EU as a whole.

British Balance of Competence Reviews, Part III: More reform than renegotiation or repatriation. EPIN [Working] Paper No. 42/December 2014. [see Abstract for I and II]

This paper, the third in a series for a CEPS project on the ‘The British Question’, is pegged on an ambitious exercise by the British government to review all the competences of the European Union on the basis of evidence submitted by independent stakeholders. The reviews considered in this paper cover the following EU policies: the single market for services, financial markets, the free movement of people, cohesion, energy, agriculture, fisheries, competition, social and employment policies, and fundamental rights. The declared objective of Prime Minister Cameron is to secure a ‘new settlement’ between the UK and the EU. From political speeches in the UK one can identify three different types of possible demand: reform of EU policies, renegotiation of the UK’s specific terms of membership, and repatriation of competences from the EU back to the member states. As most of the reviews are now complete, three points are becoming increasingly clear: i) The reform agenda – past, present or future - concerns virtually every branch of EU policy, including several cases reviewed here that are central to stated UK economic interests. The argument that the EU is ‘unreformable’ is shown to be a myth. ii) The highly sensitive cases of immigration from the EU and social policies may translate into requests for renegotiation of specific conditions for the UK, but further large-scale opt-outs, as in the case of the euro and justice and home affairs, are implausible. iii) While demands for repatriation of EU competences are voiced in general terms in public debate in the UK, no specific proposals emerge from the evidence as regards competences at the level at which they are identified in the treaties, and there is no chance of achieving consensus for such ideas among member states. Michael Emerson and Steven Blockmans, “British Balance of Competence Reviews, Part I: ‘Competences about right, so far’”, CEPS/EPIN Working Paper No. 35, October 2013 (www.ceps.eu/book/british-balance-competence-reviews-part-i-%E2%80%98competences-about-right-so-far%E2%80%99)(http://aei.pitt.edu/45599/); Michael Emerson, Steven Blockmans, Steve Peers and Michael Wriglesworth, “British Balance of Competence Reviews, Part II: Again, a huge contradiction between the evidence and Eurosceptic populism”, CEPS/EPIN Working Paper No. 40, June 2014 (www.ceps.eu/book/british-balance-competence-reviews-part-ii-again-huge-contradiction-between-evidence-and-eurosc)(http://aei.pitt.edu/52452/).