Tumor-specific CD4 T cells instruct monocyte fate in pancreatic ductal adenocarcinoma
Michael T. Patterson, Adam L. Burrack, Yingzheng Xu, Grant H. Hickok, Zoe C. Schmiechen, Samuel Becker, Eduardo Cruz-Hinojoza, Patricia R. Schrank, Ainsley E. Kennedy, Maria Firulyova, Ebony A. Miller, Konstantin Zaitsev, Jesse W. Williams, Ingunn M. Stromnes
Abstract
Pancreatic ductal adenocarcinoma (PDA) orchestrates a suppressive tumor microenvironment that fosters immunotherapy resistance. Tumor-associated macrophages (TAMs) are the principal immune cell infiltrating PDA and are heterogeneous. Here, by employing macrophage fate-mapping approaches and single-cell RNA sequencing, we show that monocytes give rise to most macrophage subsets in PDA. Tumor-specific CD4, but not CD8, T cells promote monocyte differentiation into MHCII hi anti-tumor macrophages. By conditional major histocompatibility complex (MHC) class II deletion on monocyte-derived macrophages, we show that tumor antigen presentation is required for instructing monocyte differentiation into anti-tumor macrophages, promoting Th1 cells, abrogating Treg cells, and mitigating CD8 T cell exhaustion. Non-redundant IFNγ and CD40 promote MHCII hi anti-tumor macrophages. Intratumoral monocytes adopt a pro-tumor fate indistinguishable from that of tissue-resident macrophages following loss of macrophage MHC class II or tumor-specific CD4 T cells. Thus, tumor antigen presentation by macrophages to CD4 T cells dictates TAM fate and is a major determinant of macrophage heterogeneity in cancer.