CD4+CD25+ regulatory T cells inhibit natural killer cell functions in a transforming growth factor–β–dependent manner

Tumor growth promotes the expansion of CD4+CD25+ regulatory T (T reg) cells that counteract T cell–mediated immune responses. An inverse correlation between natural killer (NK) cell activation and T reg cell expansion in tumor-bearing patients, shown here, prompted us to address the role of T reg cells in controlling innate antitumor immunity. Our experiments indicate that human T reg cells expressed membrane-bound transforming growth factor (TGF)–β, which directly inhibited NK cell effector functions and down-regulated NKG2D receptors on the NK cell surface. Adoptive transfer of wild-type T reg cells but not TGF-β−/− T reg cells into nude mice suppressed NK cell–mediated cytotoxicity, reduced NKG2D receptor expression, and accelerated the growth of tumors that are normally controlled by NK cells. Conversely, the depletion of mouse T reg cells exacerbated NK cell proliferation and cytotoxicity in vivo. Human NK cell–mediated tumor recognition could also be restored by depletion of T reg cells from tumor-infiltrating lymphocytes. These findings support a role for T reg cells in blunting the NK cell arm of the innate immune system

High-resolution laser system for the S3-Low Energy Branch

In this paper we present the first high-resolution laser spectroscopy results obtained at the GISELE laser laboratory of the GANIL-SPIRAL2 facility, in preparation for the first experiments with the S$^3$-Low Energy Branch. Studies of neutron-deficient radioactive isotopes of erbium and tin represent the first physics cases to be studied at S$^3$. The measured isotope-shift and hyperfine structure data are presented for stable isotopes of these elements. The erbium isotopes were studied using the $4f^{12}6s^2$ $^3H_6 \rightarrow 4f^{12}(^3 H)6s6p$ $J = 5$ atomic transition (415 nm) and the tin isotopes were studied by the $5s^25p^2 (^3P_0) \rightarrow 5s^25p6s (^3P_1)$ atomic transition (286.4 nm), and are used as a benchmark of the laser setup. Additionally, the tin isotopes were studied by the $5s^25p6s (^3P_1) \rightarrow 5s^25p6p (^3P_2)$ atomic transition (811.6 nm), for which new isotope-shift data was obtained and the corresponding field-shift $F_{812}$ and mass-shift $M_{812}$ factors are presented

High resolution spectroscopy of the hyperfine structure splitting in97,99^{97,99}Tc

Resonance ionization mass spectrometry is an efficient tool for detecting trace amounts of long-lived radio-isotopes in environmental samples. For absolute quantification a tracer with identical atomic properties and chemical behavior is needed to prevent a possible dependency onto the absolute efficiency for the analytical method. For an application in$^{99}$Tc, the isotope$^{97}$Tc could serve as a potential tracer. Therefore the optical transitions of an efficient ionization scheme for technetium were investigated for the two odd mass isotopes$^{97,99}$Tc, both with a nuclear spin of I= $\frac {9}{2}$ . Using a pulsed, single mode laser with narrow bandwidth, the hyperfine structures (HFS) of two transitions were fully resolved. The observed isotope shift is small in comparison to the width of the hyperfine structure splitting. This is ideal for the application of$^{97}$Tc as tracer isotope for$^{99}$Tc quantification. The evaluation of the observed HFS splitting results in a first experimental value for the magnetic dipole for$^{97}$Tc of μ=+5.82(9) μ$_{N}$

In-gas-jet laser spectroscopy of No 254 with JetRIS

International audienceHere we report online results with the in-gas-Jet Resonance Ionization Spectroscopy (JetRIS) apparatus. The S 0 1 ↔ P 1 1 transition of No 254 was successfully measured with sub-GHz resolution, marking a fivefold improvement over previous measurements. Recent developments in laser spectroscopy have allowed access to more exotic nuclei, but measurements of the heavy actinide region have been limited by line broadening mechanisms, limiting the precision with which nuclear properties can be deduced from the hyperfine spectrum. JetRIS provides a method to measure the heavy actinide region with a high level of sensitivity and higher resolution than previous experiments. The offline and online characterizations of the system are reported, and future perspectives are presented. Published by the American Physical Society 202