Mouse pulmonary interstitial macrophages mediate the pro-tumorigenic effects of IL-9.

Although IL-9 has potent anti-tumor activity in adoptive cell transfer therapy, some models suggest that it can promote tumor growth. Here, we show that IL-9 signaling is associated with poor outcomes in patients with various forms of lung cancer, and is required for lung tumor growth in multiple mouse models. CD4 T cell-derived IL-9 promotes the expansion of both CD11c and CD11c interstitial macrophage populations in lung tumor models.

Donor lung derived myeloid and plasmacytoid dendritic cells differentially regulate T cell proliferation and cytokine production.

Background: Direct allorecognition, i.e., donor lung-derived dendritic cells (DCs) stimulating recipient-derived T lymphocytes, is believed to be the key mechanism of lung allograft rejection.