Beta-Amyloid Peptides Enhance the Proliferative Response of Activated CD4+CD28+ Lymphocytes from Alzheimer Disease Patients and from Healthy Elderly

Alzheimer's disease (AD) is the most frequent form of dementia among elderly. Despite the vast amount of literature on non-specific immune mechanisms in AD there is still little information about the potential antigen-specific immune response in this pathology. It is known that early stages of AD include β-amyloid (Aβ)- reactive antibodies production and inflammatory response. Despite some evidence gathered proving cellular immune response background in AD pathology, the specific reactions of CD4+ and CD8+ cells remain unknown as the previous investigations yielded conflicting results. Here we investigated the CD4+CD28+ population of human peripheral blood T cells and showed that soluble β-amyloids alone were unable to stimulate these cells to proliferate significantly, resulting only in minor, probably antigen-specific, proliferative response. On the other hand, the exposure of in vitro pre-stimulated lymphocytes to soluble Aβ peptides significantly enhanced the proliferative response of these cells which had also lead to increased levels of TNF, IL-10 and IL-6. We also proved that Aβ peptide-enhanced proliferative response of CD4+CD28+ cells is autonomous and independent from disease status while being associated with the initial, ex vivo activation status of the CD4+ cells. In conclusion, we suggest that the effect of Aβ peptides on the immune system of AD patients does not depend on the specific reactivity to Aβ epitope(s), but is rather a consequence of an unspecific modulation of the cell cycle dynamics and cytokine production by T cells, occurring simultaneously in a huge proportion of Aβ peptide-exposed T lymphocytes and affecting the immune system performance

Effect of partially ionized high-Z atoms on fast electron dynamics in tokamak plasmas

International audienceThe dynamics of fast electrons driven inductively or by resonant interactions with radio-frequency waves is known to be highly sensitive to the presence of impurities in hot magnetized hydrogen plasmas. The possibility to use tungsten for the ITER divertor, thanks to its low tritium retention and high melting temperature, has raised the question of the impact of partially ionized high-Z atoms on current drive efficiency by enhancing pitch-angle scattering but also collisional slowing-down and inelastic scattering. Pioneering work on the impact of the screening effect of partially ionized atoms in kinetic calculations was carried out primarily for the problem of runaway electron mitigation in very cold post-disruptive plasmas [1]. In the present paper, this approach is adapted and extended to regular plasma regimes, allowing to take into account any type of high-Z metallic impurity in the plasma core on the fast electron dynamics and the non-thermal bremsstrahlung. This work has been implemented in LUKE Fokker-Planck solver [2] and the quantum relativistic radiation code R5-X2 [3] and the impact of partially ionized high-Z impurities on Lower Hybrid driven current in the WEST tokamak has been investigated

Effect of partially ionized high-Z atoms on fast dynamics electron tokamak plasmas

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The14N(p,g)15O measurement at low energy

The 14N(p,γ)15O reaction has been investigated by the LUNA experiment at the National Laboratory of Gran Sasso (LNGS). This study has been performed with two different technical set-ups. The first one, suitable for the detection of γ-rays coming from the single transitions, has been realized with a HPGe detector and a solid target. The second has been made of a BGO summing crystal as a detector and a windowless gas target. The high-detection efficiency and the target purity of the gas target set-up allowed to measure the total S-factor down to Ec.m. = 71 keV