Expanded human blood-derived γδT cells display potent antigen-presentation functions

Cell-based immunotherapy strategies target tumors directly (via cytolytic effector cells) or aim at mobilizing endogenous anti-tumor immunity. The latter approach includes dendritic cells (DC) most frequently in the form of in vitro cultured peripheral blood monocytes-derived DC. Human blood \u3b3\u3b4T cells are selective for a single class of non-peptide agonists ("phosphoantigens") and develop into potent antigen-presenting cells (APC), termed \u3b3\u3b4T-APC within 1-3 days of in vitro culture. Availability of large numbers of \u3b3\u3b4T-APC would be advantageous for use as a novel cellular vaccine. We here report optimal \u3b3\u3b4T cell expansion (>107cells/ml blood) when peripheral blood mononuclear cells (PBMC) from healthy individuals and melanoma patients were stimulated with zoledronate and then cultured for 14 days in the presence of IL-2 and IL-15, yielding \u3b3\u3b4T cell cultures of variable purity (77 \ub1 21 and 56 \ub1 26%, respectively). They resembled effector memory \u3b1\u3b2T (TEM) cells and retained full functionality as assessed by in vitro tumor cell killing as well as secretion of pro-inflammatory cytokines (IFN\u3b3, TNF\u3b1) and cell proliferation in response to stimulation with phosphoantigens. Importantly, day 14 \u3b3\u3b4T cells expressed numerous APC-related cell surface markers and, in agreement, displayed potent in vitro APC functions. Day 14 \u3b3\u3b4T cells from PBMC of patients with cancer were equally effective as their counterparts derived from blood of healthy individuals and triggered potent CD8+ \u3b1\u3b2T cell responses following processing and cross-presentation of simple (influenza M1) and complex (tuberculin purified protein derivative) protein antigens. Of note, and in clear contrast to peripheral blood \u3b3\u3b4T cells, the ability of day 14 \u3b3\u3b4T cells to trigger antigen-specific \u3b1\u3b2T cell responses did not depend on re-stimulation. We conclude that day 14 \u3b3\u3b4T cell cultures provide a convenient source of autologous APC for use in immunotherapy of patients with various cancers

MerTK expressing hepatic macrophages promote the resolution of inflammation in acute liver failure

Objective: Acute liver failure (ALF) is characterised by overwhelming hepatocyte death and liver inflammation with massive infiltration of myeloid cells in necrotic areas. The mechanisms underlying resolution of acute hepatic inflammation are largely unknown. Here, we aimed to investigate the impact of Mer tyrosine kinase (MerTK) during ALF and also examine how the microenvironmental mediator, secretory leucocyte protease inhibitor (SLPI), governs this response. Design: Flow cytometry, immunohistochemistry, confocal imaging and gene expression analyses determined the phenotype, functional/transcriptomic profile and tissue topography of MerTK+ monocytes/macrophages in ALF, healthy and disease controls. The temporal evolution of macrophage MerTK expression and its impact on resolution was examined in APAP-induced acute liver injury using wild-type (WT) and Mer-deficient (Mer−/−) mice. SLPI effects on hepatic myeloid cells were determined in vitro and in vivo using APAP-treated WT mice. Results: We demonstrate a significant expansion of resolution-like MerTK+HLA-DRhigh cells in circulatory and tissue compartments of patients with ALF. Compared with WT mice which show an increase of MerTK+MHCIIhigh macrophages during the resolution phase in ALF, APAP-treated Mer−/− mice exhibit persistent liver injury and inflammation, characterised by a decreased proportion of resident Kupffer cells and increased number of neutrophils. Both in vitro and in APAP-treated mice, SLPI reprogrammes myeloid cells towards resolution responses through induction of a MerTK+HLA-DRhigh phenotype which promotes neutrophil apoptosis and their subsequent clearance. Conclusions: We identify a hepatoprotective, MerTK+, macrophage phenotype that evolves during the resolution phase following ALF and represents a novel immunotherapeutic target to promote resolution responses following acute liver injury