Allergenicity Kit, Cellular Analysis of Allergy consists of an optimized three-color combination of fluorescent monoclonal antibodies, an activation solution, a positive control for IgE-mediated basophil activation, a stop solution, a lysing solution and a fixative solution. The Allergenicity Kit is intended for the identification of resting and activated basophils based on an accurate basophils gating tool (utilizing CRTH2posCD203cposCD3neg). The analysis is performed on whole blood specimens. The cell population of interest is stained with monoclonal antibodies in the presence of the allergen or controls. Erythrocytes are then lysed prior to flow cytometry analysis. Once T lymphocytes (CD3+ cells) are excluded, basophils are identified using CRTH2 and CD203c expression. Non-activated and resting basophils are CRTH2posCD203cdimCD3neg, whereas in vitro activated basophils are CRTH2posCD203cbrightCD3neg. The flow cytometer must be equipped to detect forward scatter, side scatter and three fluorescence channels allowing the analysis of FITC-, PE-, and PC7- conjugated antibodies.