IL-33 administration, able to increase the eosinophil count by bone marrow stimulation, seems to accelerate tumor progression and development of metastases in breast cancer mice models through intratumoral accumulation of immunosuppressive cells (myeloid derived suppressor cells (MDSC), Tregs, and M2 macrophages), reducing the cytotoxicity and tumor infiltration of NK cells, and inducing neovascularization [59,60]. The gene discussed is IL33; the disease is breast cancer.