PDCD1 and allergic disease: The PD-1 and PD-L1 gene expression was evaluated in the different subgroups of the CRSwNP patients, including subjects with chronic rhinosinusitis with nasal polyps, chronic rhinosinusitis with nasal polyp and allergy and chronic rhinosinusitis with nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (N-ERD).