Immunology in the Clinic Review Series; focus on allergies: basophils as biomarkers for assessing immune modulation

Abstract

Allergen-specific immunotherapy is an effective clinical treatment for hypersensitivity to many allergens. Studies of basophils during immunotherapy have provided insight into underlying immune mechanisms and support the potential use of basophil activation as a biomarker of clinical outcomes. This review examines the evidence for different pathways of basophil modulation associated with various forms of immunotherapy. Better understanding the molecular mechanisms of basophil activation and desensitization and the relationship between suppression of these effector cells to clinical outcomes holds promise for further development and improvement in potential therapies for allergic diseases.

Fig. 1

Markers of basophil activation. Basophils, identified on scatter characteristics and as CD123⁺CRTH2⁺ HLA-DR^– cells, from a mouse allergic donor demonstrate up-regulation of CD203c and increased frequency of CD63^hi with activation.

Fig. 2

Characteristics of the basophil dose–response curve. Plotting of immunoglobulin (Ig)E-mediated basophil activation with increasing antigen doses leads to a dose–response curve as above. A. The maximal dose response is also known as basophil reactivity, and the effective dose at 50% of the maximal dose response (ED50) is also referred to as basophil sensitivity. *Refers the supraoptimal part of the dose–response curve. B. Another method of comparison of basophil curves could use the area under the curve (AUC). C. Variation in basophil maximal dose response between donors with similar basophil reactivity. D. Variation in basophil reactivity between donors with similar maximal dose response.