Myeloid suppressor cells regulate the adaptive immune response to cancer
J. Clin. Invest. Alan B. Frey, et al. 116:2587 doi:10.1172/JCI29906 [Go to this article.]

Figure 1
Immunosuppressive effects of tumor-induced MSCs on antitumor CD8⁺ T lymphocytes. Previous work has shown that certain factors that enhance myelopoiesis are produced either by tumors or in response to tumor growth (i). In this issue of the JCI, Gallina et al. (10) demonstrate that release of IFN-γ by CD8⁺ T lymphocytes (ii) triggers MSCs to release IL-13 and IFN-γ (iii). This results in the production and activation in an autocrine manner of the enzymes iNOS and Arginase I (iv), the downstream effects of which can inhibit CD8⁺ T cell proliferation and activation or trigger T cell apoptosis (v). Therapeutic approaches to lifting this MSC-induced immunosuppression during cancer might include targeted deletion of IL-4Rα⁺ cells (MSCs), blockade of IL-4Rα, inhibition of STAT-3–dependent pre-MSC maturation into active MSCs, and Arginase I or iNOS inhibition. Figure modified from Gallina et al. (10).