The primary objective of this study is to see whether systemic corticosteroids (such as Prednisone) have an effect on the peripheral blood Treg and Th17 function in patients with CRS. Patients are taking prednisone as part of their routine medical care.

Inclusion Criteria:

• Diagnosis of CRS.
• A CT scan performed in the last year depicting the severity of the disease or nasal polyps on endoscopy.
• Symptomatic at the time of entry into the study as determined by scores ≥ 1.4 on the Rhinosinusitis disability index

Exclusion Criteria:

• Women who are pregnant or breastfeeding.
• Patients with severe medical condition(s) that in the view of the investigator prohibits participation in the study (heart, lung, kidney, diabetes, osteoporosis, cataracts, glaucoma, neurological, oncologic, liver disease or a contraindication to taking prednisone).
• Use of any other investigational agent in the last 30 days.
• Use of clinical drugs like antihistamines, leukotriene modifiers, intranasal steroids, systemic corticosteroids in the last 15 days or immunotherapy in the last year.
• Upper respiratory infection within 14 days of study start
• Smoking within the last 2 months.

Patients with seasonal allergies taking prednisone and normal controls form the community.