Potential roles of eosinophils in cancer therapy: epidemiological studies, experimental models, and clinical pathology

Eosinophils play important roles in allergic diseases as well as during helminth infection. As multifunctional leukocytes, eosinophils have also been indicated in anti-cancer immunity. Published studies have suggested an association between allergic conditions and a trend of decreased risk in numerous malignances. Moreover, eosinophil infiltration in tumor tissue is considered an independent prognostic factor. Eosinophils are often recruited to tumor sites, where eosinophil granule proteins and cytokines are released upon activation, which in turn damage and kill tumor cells. In the last decade, a number of patents based on potential cancer therapy using eosinophilic cytokines have been awarded. In this article, we review the current findings on epidemiology, experimental models, clinical pathology, and molecular mechanisms involved in the response of eosinophils towards cancer. Moreover, we discuss promising targeted therapies with eosinophilic cytokines as a novel perspective to combat cancer.