Immature myeloid cells directly contribute to skin tumor development by recruiting IL-17-producing CD4+ T cells.

Evidence links chronic inflammation with cancer, but cellular mechanisms involved in this process remain unclear. We have demonstrated that in humans, inflammatory conditions that predispose to development of skin and colon tumors are associated with accumulation in tissues of CD33+S100A9+ cells, the phenotype typical for myeloid-derived suppressor cells in cancer or immature myeloid cells (IMCs) in tumor-free hosts. To identify the direct role of these cells in tumor development, we used S100A9 transgenic mice to create the conditions for topical accumulation of these cells in the skin in the absence of infection or tissue damage.

Myeloid-derived suppressor cells in the development of lung cancer.

Myeloid-derived suppressor cells (MDSC) are widely implicated in immune suppression associated with tumor progression and chronic inflammation. However, very little is known about their possible role in tumor development. Here, we evaluated the role of MDSC in two experimental models of lung cancer: inflammation-associated lung cancer caused by chemical carcinogen urethane in combination with exposure to cigarette smoke; and a transgenic CC10Tg model not associated with inflammation.