Tailoring the Electron and Hole Landé Factors in Lead Halide Perovskite Nanocrystals by Quantum Confinement and Halide Exchange.

The tunability of the optical properties of lead halide perovskite nanocrystals makes them highly appealing for applications. Halide anion exchange and quantum confinement enable tailoring of the band gap. For spintronics, the Landé g-factors of electrons and holes are essential. Using empirical tight-binding and k·p methods, we calculate them for nanocrystals of all-inorganic lead halide perovskites CsPbX3 (X = I, Br, Cl). The hole g-factor band gap dependence follows the universal law found for bulk perovskites, while for electrons, a considerable modification is predicted. Based on the k·p analysis, we conclude that this difference arises from the interaction of the bottom conduction band with the spin-orbit split electron states. These predictions are confirmed experimentally for electron and hole g-factors in CsPbI3 nanocrystals in a glass matrix, measured by time-resolved Faraday ellipticity in a magnetic field at cryogenic temperatures.

In Vitro Model of Suppression of the Alloantigen Response by Tolerogenic Dendritic Cells Transfected with Personalized DNA Constructs Encoding HLA Epitopes.

BACKGROUND: A search for efficient graft rejection modulation techniques for the promotion of durable engraftment remains to be a matter of close study all over the world. Despite the variety of immunosuppressive drugs, the schemes currently used show a lack of selectivity and have a number of side effects. Here we investigated an approach for the induction of antigen-specific tolerance in a human "stimulator-responder" model in vitro, using dendritic cells (DCs) transfected with designed DNA constructs encoding the stimulator's major histocompatibility complex (MHC) epitopes. METHODS: The object of the study is peripheral blood mononuclear cells (PBMCs) from 10 healthy donors. To induce antigen-specific tolerance, personalized DNA constructs were created for five responder-stimulator pairs, based on the sequences of donors' and recipients' MHCs. DNA sequencing was performed to select epitopes for incorporation into genetic constructs. A mixed lymphocyte culture assay was used (i) to assess the proliferative response in both directions for all possible stimulator-responder pairs (90 reactions) and (ii) to assess the tolerogenic properties of the generated transfected DCs (5 reactions). RESULTS: A significant increase in the amounts of FoxP3+ CD4+CD25+ cells and in IL-10 production was shown in culture of donor mononuclear cells after co-cultivation with the responder's dendritic cells transfected with donor-specific plasmids. The tolerogenic cultures generated using tolerogenic DCs transfected with MHC epitopes had a significantly greater ability to inhibit the proliferation of autologous MNCs in response to an allogeneic MHC stimulus. CONCLUSIONS: The produced DCs transfected with DNA constructs against HLA stimulating epitopes exhibited tolerogenic properties and may be used to develop antigen-specific tolerance. Thus, we proposed a perspective approach to the induction of antigen-specific tolerance, which should subsequently be studied for use in clinical practice.

Submillisecond Spin Relaxation in CsPb(Cl,Br)3 Perovskite Nanocrystals in a Glass Matrix.

Lead halide perovskite nanocrystals in a glass matrix are a promising platform for optoelectronic applications due to their excellent optical properties combined with outstanding stability against the environment. We reveal the potential of this system for spintronics by studying the electron spin properties of CsPb(Cl,Br)3 nanocrystals in a fluorophosphate glass matrix. Using optical spin orientation and spin depolarization with a radio frequency field, we measure longitudinal spin relaxation time, T1, reaching several hundreds of microseconds at low temperatures. This time T1 corresponds to a spin state with a small g factor, which we attribute to a weakly exchange-coupled electron-hole pair with antiparallel spins.

Dendritic Cells Transfected with MHC Antigenic Determinants of CBA Mice Induce Antigen-Specific Tolerance in C57Bl/6 Mice.

BACKGROUND: Nonspecific immunosuppressive therapy for graft rejection and graft-versus-host disease (GVHD) is often accompanied by severe side effects such as opportunistic infections and cancers. Several approaches have been developed to suppress transplantation reactions using tolerogenic cells, including induction of FoxP3+ Tregs with antigen-loaded dendritic cells (DCs) and induction of CD4+IL-10+ cells with interleukin IL-10-producing DCs. Here, we assessed the effectiveness of both approaches in the suppression of graft rejection and GVHD. METHODS: IL-10-producing DCs were generated by the transfection of DCs with DNA constructs encoding mouse IL-10. Antigen-loaded DCs from C57BL/6 mice were generated by transfection with DNA constructs encoding antigenic determinants from the H2 locus of CBA mice which differ from the homologous antigenic determinants of C57BL/6 mice. RESULTS: We found that both IL-10-producing DCs and antigen-loaded immature DCs could suppress graft rejection and GVHD but through distinct nonspecific and antigen-specific mechanisms, respectively. Discussion. We provide data that the novel approach for DCs antigen loading using DNA constructs encoding distinct homologous determinants derived from major histocompatibility complex genes is effective in antigen-specific suppression of transplantation reactions. Such an approach eliminates the necessity of donor material use and may be useful in immunosuppressive therapy side effects prevention.

Autologous dendritic cells and activated cytotoxic T­cells as combination therapy for breast cancer.

Breast cancer is the most common oncological pathology in women worldwide. Techniques for improving the clinical parameters of patients undergoing combination therapy for breast cancer are currently under development. A type of treatment employing dendritic cells (DCs) and cytotoxic DC­induced antigen­specific T lymphocytes efficiently eliminates residual cancer cells that are the key cause of tumor recurrence and metastasis. In the present study, DCs and activated lymphocytes (treated with IL­12 and IL­18) were isolated from the peripheral blood of patients with breast cancer, using a lysate of tumor tissue as antigen. The patients received the cells as part of adjuvant or neoadjuvant regimens (stage IV disease or progression). Evaluation of immunity was performed at 3 and 6 months after terminating immunotherapy. Evaluation of the disease­free period was performed for 3 years after surgery. The use of antigen­loaded autologous DCs combined with mononuclear cells with increased cytotoxic activity following Th1 polarization reduced the populations of immunosuppressive cells. The results of the present study demonstrated that the investigated cellular immunotherapy for breast cancer is safe, reduces the risk of relapse and metastasis, and improves immunity by reducing the number of regulatory T cells. Therefore, this therapeutic strategy may represent a novel approach to combating distant metastases of breast cancer.