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We have ablated HMGB1 in CD11c+ cells (DCH mice) to evaluate the role of DC HMGB1 loss, immunologically, in vaccination strategies to tumor and in vivo in the setting of pancreatic carcinogenesis. HMGB1 is a chromatin-associated molecule regulating the response to several transcriptional factors, as well as promoting cytosolic autophagy in the setting of stress. When released extracellularly following necrosis or during stress, it serves as a damage associated molecular pattern (DAMP) molecule. DCH mice represent a novel model to answer several questions. First, is HMGB1 necessary for DC function? Second, can KO-DCs confer protection as therapeutic vaccines in anti-tumor models of PDAC? Lastly, how is carcinogenesis affected in a Kras-driven model of pancreatic neoplasia (KC mice) in the presence of KO-DCs? KO-DCs to be less responsive to maturational stimuli, have inhibited T cell stimulatory capacity, and skew naïve T cells towards regulatory phenotypes. KO-DCs fail to initiate anti-tumor immunity in multiple tumor vaccine models compared to controls. Unexpectedly, DCH mice inoculated with transplantable (pancreatic and colorectal cancer) tumor cells were significantly protected from tumor growth. BM transplants from DCH mice into KC mice resulted in significant inhibition of neoplasia and the associated inflammatory infiltrate. As DCs actively secrete HMGB1 during maturation, we next examined the role of the HMGB1 receptor, the receptor for advanced glycation-endproducts (RAGE) in the promotion of PDAC. We back-crossed RAGE-KO mice into the KC strain (KCR) and evaluated the role of RAGE in modulating the myeloid response to pancreatic carcinogenesis. We observed a significant delay in neoplasia in KCR mice and a correlation with a reduction in the accumulation of myeloid-derived suppressor cells (MDSCs). In the absence of RAGE and the development of malignant precursor lesions, non-immunosuppressive macrophages were detected in both the spleens and pancreata of K