IL15 synergizes with radiotherapy to reprogram the tumor immune contexture through a dendritic cell connection

IL15 is a key cytokine for the activation and survival of anti-tumor effectors CD8⁺ T and NK cells. Recently published preclinical studies demonstrate that the therapeutic activity of IL15 requires conventional dendritic cells type 1 (cDC1). Radiotherapy cooperates with IL15 by enhancing cDC1 tumor infiltration via interferon type 1 activation.

Delta-Globin Gene Expression Is Enhanced in vivo by Interferon Type I

Beta hemoglobinopathies are widely spread monogenic lethal diseases. Delta-globin gene activation has been proposed as a possible approach for curing these pathologies. The therapeutic potential of delta-globin, the non-alpha component of Hemoglobin A₂ (α2δ2; HbA2), has been demonstrated in a mouse model of beta thalassemia, while its anti-sickling effect, comparable to that of gamma globin, was established some time ago. Here we show that the delta-globin mRNA level is considerably increased in a Deoxyribonuclease II-alpha knockout mouse model in which type 1 interferon (interferon beta, IFNb) is activated. IFNb activation in the fetal liver improves the delta-globin mRNA level, while the beta-globin mRNA level is significantly reduced. In addition, we show that HbA2 is significantly increased in patients with multiple sclerosis under type 1 interferon treatment. Our results represent a proof of principle that delta-globin expression can be enhanced through the use of molecules. This observation is potentially interesting in view of a pharmacological approach able to increase the HbA2 level.

CD11c(+)B220(+)Gr-1(+) cells in mouse lymph nodes and spleen display characteristics of plasmacytoid dendritic cells

Human plasmacytoid dendritic cells (pDCs) are major producers of IFNalpha, are activated by CpG motifs, and are believed to enter lymph nodes (LNs) via L-selectin dependent extravasation across high endothelial venules. To identify a similar murine DC type, CD11c(+) cells in the LNs of L-selectin-deficient and control BALB/c mice were compared, revealing a population of CD11c(+)CD11b(-) cells that is reduced 85% in the LNs of L-selectin-deficient mice. These cells are Gr-1(+)B220(+)CD19(-), either CD4(+) or CD8(+), and localize within T cell zones of LNs. Freshly isolated CD11c(+)Gr-1(+) cells express major histocompatibility complex class II at low levels, display a plasmacytoid morphology, and survive poorly in culture. Their survival is increased and they develop a DC-like morphology in interleukin 3 and CpG. Like human pDCs, CD11c(+)Gr-1(+) cells stimulate T cell proliferation after activation with CpG and produce IFNalpha after stimulation with influenza virus. These cells also display a strain-specific variation in frequency, being fivefold increased in the LNs of BALB/c relative to C57BL/6 mice. These CD11c(+)CD11b(-)B220(+)Gr-1(+) cells appear to be the murine equivalent of human pDCs.