Abstract:INTRODUCTION: The pathogenesis of chronic rhinosinusitis (CRS) with nasal polyps (CRSwNPs) is not yet completely understood. Based on current knowledge, the infiltration of mast cells and eosinophils in nasal polyps (NPs) plays an important role. This study aimed to investigate the interplay of asthma and allergy etiopathology in CRSwNPs patients by specifically studying tissue mast cells and eosinophils and the pro-inflammatory marker CD48. METHODS: Immunohistochemistry was used to assess eosinophils, mast cells, and CD48 expressing eosinophils infiltrating NPs, and flow cytometry was used to assess surface receptors expression on eosinophils from digested NPs. RESULTS: Immunohistochemical analyses showed that mast cell infiltration in NPs is higher in allergic patients in comparison to nonallergic patients; eosinophils infiltration in asthmatic NPs was significantly elevated in comparison to the nonasthmatic NPs, and membrane CD48 (mCD48) expression on eosinophils infiltrating nonallergic asthmatic NPs was highly elevated in comparison to the other subgroups. Similarly, mCD48 and its high-affinity ligand m2B4's expression on eosinophils from enzymatically digested NPs were significantly higher in nonallergic asthmatics in comparison to allergic asthmatics. CONCLUSIONS: Eosinophil infiltration in NPs for asthmatic patients, and mast cell infiltration for allergic patients, may be used as reliable biomarkers for endotyping CRSwNPs. In addition, CD48 in asthmatic patients who developed CRSwNPs could be regarded as a potential target for treatment.