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Expression of the B7 family molecules in acute myeloid leukemia (AML) has been demonstrated by independent clinical studies. Intriguingly, the expression of the most potent costimulatory molecules B7-2 (CD86) and B7-H2 (ICOS Ligand) on AML cells has been associated with poor prognosis and disease severity. Here, this phenomenon was modeled in vitro with the myeloid leukemia cell line HL-60, which is capable of differentiating through the FAB M2/M3 and M4/M5 immunophenotypes. These derivatives of HL-60 harbored a B7-2+ subpopulation and recapitulated the distribution of B7 ligands previously reported in primary AML cases. B7-2+ AML cells significantly contributed to T-cell responses. This costimulatory activity enabled helper (Th)-cell activation, proliferation, and production of Th1-associated cytokines. Conversely, even a short-term incubation with stimulated T cells resulted in upregulation of inhibitory B7-H1 (PD-L1) and B7-DC (PD-L2), and downregulation of stimulatory B7-H2 molecules on leukemia cells. Purified from iHL-60-T-cell co-cultures, these myeloid leukemia cells severely suppressed Th-cell responses specifically through the PD-1 pathway. In conclusion, Th-cell responses can be directly supported by B7-2+ leukemia subpopulations. However, this interaction can facilitate the acquisition of a suppressive character that may contribute to immune evasion in myeloid leukemia. [ABSTRACT FROM AUTHOR]

Ultrasound is the most commonly used clinical imaging modality. However, in applications requiring cell‐labeling, the large size and short active lifetime of ultrasound contrast agents limit their longitudinal use. Here, 100 nm radius, clinically applicable, polymeric nanoparticles containing a liquid perfluorocarbon, which enhance ultrasound contrast during repeated ultrasound imaging over the course of at least 48 h, are described. The perfluorocarbon enables monitoring the nanoparticles with quantitative 19F magnetic resonance imaging, making these particles effective multimodal imaging agents. Unlike typical core–shell perfluorocarbon‐based ultrasound contrast agents, these nanoparticles have an atypical fractal internal structure. The nonvaporizing highly hydrophobic perfluorocarbon forms multiple cores within the polymeric matrix and is, surprisingly, hydrated with water, as determined from small‐angle neutron scattering and nuclear magnetic resonance spectroscopy. Finally, the nanoparticles are used to image therapeutic dendritic cells with ultrasound in vivo, as well as with 19F MRI and fluorescence imaging, demonstrating their potential for long‐term in vivo multimodal imaging. [ABSTRACT FROM AUTHOR]

Adaptive immunity relies on dendritic cell (DC) migration to transport antigens from tissues to lymph nodes. Galectins, a family of β-galactoside-binding proteins, control cell membrane organisation, exerting crucial roles in multiple physiological processes. Here, we report a novel mechanism underlying cell polarity and uropod retraction. We demonstrate that galectin-9 regulates chemokine-driven and basal DC migration both in humans and mice, indicating a conserved function for this lectin. We identified the underlying mechanism, namely a deficiency in cell rear contractility mediated by galectin-9 interaction with CD44 that in turn regulates RhoA activity. Analysis of DC motility in the 3D tumour-microenvironment revealed galectin-9 is also required for DC infiltration. Moreover, exogenous galectin-9 rescued the motility of tumour-immunocompromised human blood DCs, validating the physiological relevance of galectin-9 in DC migration and underscoring its implications for DC-based immunotherapies. Our results identify galectin-9 as a necessary mechanistic component for DC motility and highlight a novel role for the lectin in regulating cell polarity and contractility.

Hybridoma technology is instrumental for the development of novel antibody therapeutics and diagnostics. Recent preclinical and clinical studies highlight the importance of antibody isotype for therapeutic efficacy. However, since the sequence encoding the constant domains is fixed, tuning antibody function in hybridomas has been restricted. Here, we demonstrate a versatile CRISPR/HDR platform to rapidly engineer the constant immunoglobulin domains to obtain recombinant hybridomas, which secrete antibodies in the preferred format, species, and isotype. Using this platform, we obtained recombinant hybridomas secreting Fab' fragments, isotype-switched chimeric antibodies, and Fc-silent mutants. These antibody products are stable, retain their antigen specificity, and display their intrinsic Fc-effector functions in vitro and in vivo. Furthermore, we can site-specifically attach cargo to these antibody products via chemoenzymatic modification. We believe that this versatile platform facilitates antibody engineering for the entire scientific community, empowering preclinical antibody research.

Ultrasound is the most commonly used clinical imaging modality. However, in applications requiring cell-labeling, the large size and short active lifetime of ultrasound contrast agents limit their longitudinal use. Here, 100 nm radius, clinically applicable, polymeric nanoparticles containing a liquid perfluorocarbon, which enhance ultrasound contrast during repeated ultrasound imaging over the course of at least 48 h, are described. The perfluorocarbon enables monitoring the nanoparticles with quantitative 19 F magnetic resonance imaging, making these particles effective multimodal imaging agents. Unlike typical core-shell perfluorocarbon-based ultrasound contrast agents, these nanoparticles have an atypical fractal internal structure. The nonvaporizing highly hydrophobic perfluorocarbon forms multiple cores within the polymeric matrix and is, surprisingly, hydrated with water, as determined from small-angle neutron scattering and nuclear magnetic resonance spectroscopy. Finally, the nanoparticles are used to image therapeutic dendritic cells with ultrasound in vivo, as well as with 19 F MRI and fluorescence imaging, demonstrating their potential for long-term in vivo multimodal imaging., Competing Interests: Conflict of Interest The authors declare no conflict of interest.

The activation of tumor-specific effector immune cells is key for successful immunotherapy and vaccination is a powerful strategy to induce such adaptive immune responses. However, the generation of effective anticancer vaccines is challenging. To overcome these challenges, a novel straight-forward strategy of adjuvant-induced tumor antigen assembly to generate nanovaccines with superior antigen/adjuvant loading efficiency is developed. To protect nanovaccines in circulation and to introduce additional functionalities, a biocompatible polyphenol coating is installed. The resulting functionalizable nanovaccines are equipped with a pH (low) insertion peptide (pHLIP) to facilitate endolysosomal escape and to promote cytoplasmic localization, with the aim to enhance cross-presentation of the antigen by dendritic cells to effectively activate CD8 + T cell. The results demonstrate that pHLIP-functionalized model nanovaccine can induce endolysosomal escape and enhance CD8 + T cell activation both in vitro and in vivo. Furthermore, based on the adjuvant-induced antigen assembly, nanovaccines of the clinically relevant tumor-associated antigen NY-ESO-1 are generated and show excellent capacity to elicit NY-ESO-1-specific CD8 + T cell activation, demonstrating a high potential of this functionalizable nanovaccine formulation strategy for clinical applications., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)