Chronic obstructive pulmonary disease is a type of obstructive lung disease characterized by long-term breathing problems and poor airflow. It is changed to acute exacerbation of Chronic obstructive pulmonary disease when respiratory symptoms worsen, beyond normal day-to-day variations, severely enough that changes in medication are required.

Inflammation is a core feature of acute exacerbation of Chronic obstructive pulmonary disease since it gives insight into the pathological changes causing an exacerbation. Eosinophils may play a significant role in airway inflammation in some patients with Chronic obstructive pulmonary disease.

Previous studies have indicated that eosinophilic airway inflammation is also associated with the development of severe acute exacerbation of Chronic obstructive pulmonary disease. Eosinophilic Cationic Protein has various biological activities, including antibacterial, antiviral, antiparasitic and neurotoxic functions, and it contributes to the regulation of fibroblast activity. Eosinophilic Cationic Protein also induces airway mucus secretion and interacts with the coagulation and complement systems. Eosinophilic Cationic Protein has been developed as a marker for eosinophilic disease and quantified in biological fluids including serum, bronchoalveolar lavage and nasal secretions. It is found in diseases such as allergic asthma and allergic rhinitis but also occasionally in other diseases. Only activated eosinophil granulocytes release the granule content and therefore the determination of Eosinophilic Cationic Protein concentration is a considerably more specific indicator of eosinophil inflammation than eosinophil granulocyte count in peripheral blood as serum Eosinophilic Cationic Protein levels increase during acute exacerbation of Chronic obstructive pulmonary disease

Inclusion Criteria:

• clinical features of Chronic obstructive pulmonary disease
• spirometry compatible with the GOLD criteria (Forced expiratory volume 1/ Forced vital capacity <70%) post bronchodilator.

Exclusion Criteria:

• Patients with bronchial asthma
• Asthma -Chronic obstructive pulmonary disease overlap syndrome
• Atopic patients
• Pneumothorax
• Congestive heart failure
• Cancer of any kind
• A history of major surgery in the preceding 4 weeks.
• Patients undergoing mechanical ventilation or presenting with azotaemia (serum creatinine >1.5 mg/dl).

Patients with confirmed diagnosis of Chronic obstructive pulmonary disease and acute exacerbation of Chronic obstructive pulmonary disease based on Gold guidelines, at the Chest Department and Respiratory Intensive Care Unit and chest outpatient clinic at Assiut University Hospital.