Interleukin (IL)-7 and its receptor (IL-7Rα) play important roles in regulating lymphopoiesis. Previous studies have reported that human immunodeficiency virus-1 (HIV-1) viraemia affects the ...expression of IL-7Rα, but its effects on CD4⁺ and CD8⁺ T cell memory subsets have not been studied. Using eight-colour flow cytometry, we compared the immunophenotypic patterns of CD4⁺ and CD8⁺ T cell subsets expressing IL-7Rα and activation markers, as well as circulating IL-7 levels, in three well-defined groups of HIV-1-infected subjects: successfully treated, viraemic and long-term non-progressor (LTNP). Compared with successfully treated and LTNP subjects, viraemic patients had reduced expression of IL-7Rα on both CD4⁺ and CD8⁺ T cells, particularly on central and effector memory T cell compartments, and substantially elevated expression of activation markers on CD8⁺ T cell subsets. Circulating IL-7 levels were correlated negatively with the number of CD4⁺ and CD8⁺ T cell subsets expressing IL-7Rα; these associations were stronger with CD4⁺ T cell subsets and mainly with central and effector memory cells. The expression of activation markers on CD4⁺ and CD8⁺ cell T subsets was not related to circulating IL-7 levels. A strong negative correlation was observed between central memory CD4⁺ or CD8⁺ T cells expressing IL-7Rα and those expressing activation markers, independently of IL-7 levels. Collectively, these results provide further insight on the role of unsuppressed viral load in disrupting the IL-7/IL-7Rα system and contributing to HIV-1 disease progression.
Abstract Attempts to evaluate the protective effect of live attenuated SIV vaccine strains have yielded variable results depending on the route of immunization, the level of attenuation, the level of ...divergence between the vaccine candidate and the challenge. The protective mechanisms induced by these vaccines are still not well understood. In an effort to address whether the diversity of the CD4+ T cell repertoire in cynomolgus macaques plays a role in the immunological protection following SIVmacC8 infection, we have performed a longitudinal follow-up of the CD4 repertoire by heteroduplex tracking assay in macaques mock-infected or infected with either the attenuated SIVmacC8 or its homologous SIVmacJ5 and challenged with simian-human immunodeficiency virus (SHIV89.6P). Viral load and CD4 absolute counts were determined in these animals and the presence of SHIV89.6P virus in challenged animals was evaluated by PCR and serology. In all macaques that were protected against the challenging virus, we demonstrated a reduced diversity in the CD4+ TRBV repertoire and a few dominant CD4+ T cell clones during early primary infection. In contrast, CD4 TRBV repertoire in unprotected macaques remained highly diverse. Moreover, some of the CD4 T cell clones that were expanded during primary SIV infection re-emerged after challenge suggesting their role in protection against the challenging virus. These results underline the importance of maintaining the CD4 T cell repertoire developed during acute infection and point to the restriction of the CD4 response to the vaccine as a correlate of protection.
The Egyptian Atomic Energy Authority-Plasma focus (EAEA-PF2) has been upgraded to a 5 kJ plasma focus device. Its characteristics have been investigated at various pressures and different voltages in ...a 5 kJ Mather-type plasma focus device for Ar gas. Its time-to-pinch has been measured, simulated and analyzed at different operating conditions. It is observed from the results that, the time-to-pinch decreased when either the charging voltage increased or the gas pressure decreased. In addition, the time-to-pinch is estimated theoretically using Lee model RADPF5.15. A comparison between the experimental and theoretical time-to-pinch is discussed. Also, the drive factor of plasma focus is analyzed at different pressures and charging voltages. It is noticed that, the mass and current factors are affected by changing the pressure and voltage. Finally, it is observed that, the drive factor is proportional inversely to the pressure and directly to the charging voltage.
Class I MHC tetramers have proven to be invaluable tools for following and deciphering the CD8(+) T cell response, but the development of similar reagents for detection of CD4(+) T cells based on ...class II MHC proteins has been more difficult. We evaluated fluorescent streptavidin-based oligomers of HLA-DR1 for use as reagents to analyze Ag-specific human CD4(+) T cells. Staining was blocked at low temperatures and by drugs that disrupt microfilament formation and endocytosis. Cell-associated MHC oligomers were resistant to a surface stripping protocol and were observed by microscopy in intracellular compartments. This behavior indicates that detection of CD4(+) T cells using class II MHC oligomers can depend on an active cellular process in which T cells cluster and/or endocytose their Ag receptors. T cells of identical specificity but in different activation states varied greatly in their ability to be detected by class II MHC oligomers.
The dependence of f0(980) production on the final-state charged-particle multiplicity in p–Pb collisions at sNN=5.02 TeV is reported. The production of f0(980) is measured with the ALICE detector via ...the f0(980)→π+π− decay channel in a midrapidity region of −0.5<y<0. Particle yield ratios of f0(980) to π and K⁎(892)0 are found to be decreasing with increasing charged-particle multiplicity. The magnitude of the suppression of the f0(980)/π and f0(980)/K⁎(892)0 yield ratios is found to be dependent on the transverse momentum pT, suggesting different mechanisms responsible for the measured effects. Furthermore, the nuclear modification factor QpPb of f0(980) is measured in various multiplicity ranges. The QpPb shows a strong suppression of the f0(980) production in the pT region up to about 4 GeV/c. The results on the particle yield ratios and QpPb for f0(980) may help to understand the late hadronic phase in p–Pb collisions and the nature of the internal structure of f0(980) particle.
The dependence of f0(980) production on the final-state charged-particle multiplicity in p–Pb collisions at $\sqrt{s_{NN}}$= 5.02 TeV is reported. The production of f0(980) is measured with the ALICE ...detector via the f0(980) → π+π– decay channel in a midrapidity region of –0.5 < y < 0. Particle yield ratios of f0(980) to π and K*(892)0 are found to be decreasing with increasing charged-particle multiplicity. The magnitude of the suppression of the f0(980)/π and f0(980)/K*(892)0 yield ratios is found to be dependent on the transverse momentum pT, suggesting different mechanisms responsible for the measured effects. Furthermore, the nuclear modification factor QpPb of f0(980) is measured in various multiplicity ranges. The QpPb shows a strong suppression of the f0(980) production in the pT region up to about 4 GeV/c. The results on the particle yield ratios and QpPb for f0(980) may help to understand the late hadronic phase in p–Pb collisions and the nature of the internal structure of f0(980) particle.
Charged-particle jet yields have been measured in semicentral Pb–Pb collisions at center-of-mass energy per nucleon–nucleon collision $\sqrt{s_{NN}}$= 5.02 TeV with the ALICE detector at the LHC. ...These yields are reported as a function of the jet transverse momentum, and further classified by their angle with respect to the event plane and the event shape, characterized by ellipticity, in an effort to study the path-length dependence of jet quenching. Jets were reconstructed at midrapidity from charged-particle tracks using the anti-kT algorithm with resolution parameters R = 0.2 and 0.4, with event-plane angle and event-shape values determined using information from forward scintillating detectors. The results presented in this letter show that, in semicentral Pb–Pb collisions, there is no significant difference between jet yields in predominantly isotropic and elliptical events. However, out-of-plane jets are observed to be more suppressed than in-plane jets. Further, this relative suppression is greater for low transverse momentum (< 50 GeV/c) R = 0.2 jets produced in elliptical events, with out-of-plane to in-plane jet-yield ratios varying up to 5.2σ between different event-shape classes. These results agree with previous studies indicating that jets experience azimuthally anisotropic suppression when traversing the QGP medium, and can provide additional constraints on the path-length dependence of jet energy loss.
A bstract The production yields of the Σ(1385) ± and Ξ(1530) 0 resonances are measured in pp collisions at $$ \sqrt{s} $$ s = 13 TeV with ALICE. The measurements are performed as a function of the ...charged-particle multiplicity ⟨d N ch / d η ⟩, which is related to the energy density produced in the collision. The results include transverse momentum ( p T ) distributions, p T -integrated yields, mean transverse momenta of Σ(1385) ± and Ξ(1530) 0 , as well as ratios of the p T -integrated resonance yields relative to yields of other hadron species. The Σ(1385) ± /π ± and Ξ(1530) 0 /π ± yield ratios are consistent with the trend of the enhancement of strangeness production from low to high multiplicity pp collisions, which was previously observed for strange and multi-strange baryons. The yield ratio between the measured resonances and the long-lived baryons with the same strangeness content exhibits a hint of a mild increasing trend at low multiplicity, despite too large uncertainties to exclude the flat behaviour. The results are compared with predictions from models such as EPOS-LHC and PYTHIA 8 with Rope shoving. The latter provides the best description of the multiplicity dependence of the Σ(1385) ± and Ξ(1530) 0 production in pp collisions at $$ \sqrt{s} $$ s = 13 TeV.
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