Background:Striking feature of Chronic obstructive pulmonary disease (COPD) is its inability to resolve after cigarette smoke exposure has ended, which has contributed to the possibility that the disease could also be driven by other endogenous causes, such as autoimmunity or chronic infection . Many of the pathogenetic pathways involved in COPD and its development tend to be driven by oxidative stress.

Inclusion Criteria:

• 1-Forty subjects of COPD who are non-smokers or stopped smoking for more than 6 months Based on the Global Initiative for Chronic Obstructive Lung Disease guidelines, COPD was diagnosed.9 2- Thirty subjects of non smokers healthy control

Exclusion Criteria:

• Patients of:

  1. Acute exacerbation, at the time of the study, of COPD.
  2. Any obvious abnormal lung parenchymal lesions.
  3. Lung cancer.
  4. Congestive heart failure.
  5. current smokers
  6. Drugs e.g anti-inflammatory , steroids ,analgesics, insulin , antineoplastic, antipsychotic drugs in the previous 2 weeks before the study.

Forty subjects of COPD who are non-smokers or stopped smoking for more than 6 months Based on the Global Initiative for Chronic Obstructive Lung Disease guidelines, COPD was diagnosed.9 2- Thirty subjects of non smokers healthy control