CSF2 and Patent ductus arteriosus: Our findings contrast with the prevailing view of the immune response to PDA that is based largely upon studies in GEMM in which T cells rarely infiltrate murine tumors and mostly remain sequestered in the peripancreatic lymph nodes.[7] Although MDSC recruited by tumor-derived GM-CSF have been shown to inhibit T cells from entering murine PDA tumors,[8], [9] our analysis of human PDA demonstrates that, while these tumors also produce GM-CSF, they contain both T cells and myeloid cells tightly juxtaposed in the tumor microenvironment.