Clinical and Translational Significance of Basophils in Patients with Cancer

Despite comprising a very small proportion of circulating blood leukocytes, basophils are potent immune effector cells. The high-affinity receptor for IgE (FceRI) is expressed on the basophil cell surface and powerful inflammatory mediators such as histamine, granzyme B, and cytokines are stored in dense cytoplasmic granules, ready to be secreted in response to a range of immune stimuli. Basophils play key roles in eliciting potent effector functions in allergic diseases and type 1 hypersensitivity. Beyond allergies, basophils can be recruited to tissues in chronic and autoimmune inflammation, and in response to parasitic, bacterial, and viral infections. While their activation states and functions can be influenced by Th2-biased inflammatory signals, which are also known features of several tumor types, basophils have received little attention in cancer. Here, we discuss the presence and functional significance of basophils in the circulation of cancer patients and in the tumor microenvironment (TME). Interrogating publicly available datasets, we conduct gene expression analyses to explore basophil signatures and associations with clinical outcomes in several cancers. Furthermore, we assess how basophils can be harnessed to predict hypersensitivity to cancer treatments and to monitor the desensitization of patients to oncology drugs, using assays such as the basophil activation test (BAT).

Automated summary

Basophils, despite their small proportion in circulating blood leukocytes, play significant roles as potent immune effector cells. They express high-affinity receptors for IgE and store powerful inflammatory mediators ready to be secreted. They are implicated in allergic diseases, hypersensitivity reactions, chronic inflammation, and responses to infections. Despite their activation by Th2-biased signals, which are also observed in certain tumors, basophils have been neglected in cancer research. This article discusses the presence and functional significance of basophils in cancer patients and the tumor microenvironment, exploring gene expression analyses and the potential use of basophil activation test (BAT) to predict hypersensitivity to cancer treatments and monitor patient desensitization.