Abstract: The present invention relates to methods and kits for detecting basophil cells activation. The inventors showed that fluorescent avidin binds to basophil cell surface upon degranulation and that this probe can be used to monitor basophil degranulation More specifically the present invention relates to methods for monitoring of basophil degranulation using avidin-based probes. The method of the invention described here allows to measure direct basophil degranulation following Fc?RI crosslinking with allergen. This method provides a direct measurement of degranulation by staining exteriorized granules and unambiguously detects activated basophils degranulated. The extent of the degranulation can be directly deduced from the intensity of fluorescence of fluorochrome-labelled avidin measured on basophils. When applied to allergic patient samples the avidin-based method detected efficiently specific basophil responses.