The study subjects of this research are patients with eosinophil-associated pulmonary diseases, including eosinophilic granulomatosis with polyangiitis, idiopathic hypereosinophilic syndrome, idiopathic acute eosinophilic pneumonia, idiopathic chronic eosinophilic pneumonia, and primary simple pulmonary eosinophilia. The aim is to detect eosinophil subtypes in peripheral blood based on surface protein expression, to understand the differences in eosinophil subtypes among patients with different diseases, to elucidate the significance of different eosinophil subtypes, and ultimately to provide a theoretical basis for the selection of treatment directions for patients.

Inclusion Criteria:

• For Healthy Volunteers: healthy volunteers matching the age and gender of the study subjects
• For EPD: ① Persistent eosinophil count increase>1500 per cubic millimeter for more than 6 months. ② Lack of evidence of a secondary cause of eosinophilia is required. ③ Signs and symptoms of end-organ damage presumed to be secondary to eosinophilia

Exclusion Criteria:

• Patients with concurrent definitive pulmonary infections, malignancies, or other parenchymal lung diseases;
• Patients who are unable or unwilling to cooperate with the collection of clinical information (e.g., due to mental disorders, memory impairments, etc.);
• Patients who are unable to provide informed consent.

Outpatients diagnosed with EPD who meet the inclusion criteria above.