Forkhead box protein 3 (FOXP3), a transcription factor required for development and function of regulatory T cell, and Epstein-Barr virus-induced gene 3 (EBI3), a downstream target of FOXP3, may be important in the development of chronic rhinosinusitis (CRS) with or without sinonasal polyposis (CRSwNP and CRSsNP, respectively).