Eosinophils have numerous functions for defense against pathogens, despite being only 1-5% of total circulating blood leukocytes. Most well known for their actions contributing to asthma and allergic disease, eosinophils are thought to have homeostatic roles in the thymus, uterus, mammary glands, and gut. Furthermore, recent studies have also indicated a role for eosinophils as sentinels of tumorigenesis (2-6). Our studies show that eosinophils can elicit tumoricidal activity in a dose dependent manner against a variety of cancer cells. We also attempted to optimize the cytotoxicity of eosinophils by activating different receptors. We were able to verify different methods to stimulate eosinophil activation, including incubation with cytokines, especially granulocyte macrophage, colony stimulating factor (GM-CSF), and crosslinking the Fc?R. Eosinophils do have tumoricidal activity, but further research is needed to both understand this interaction and to optimize the eosinophil's tumoricidal properties.
