Background: Too many studies are in the process of determining the probable role of immune system in the etiopathogenesis of nasal polyposis. This study was designed to identify the probable participation of Th1, Th2 lymphocytes in the induction and progression of nasal polyposis.
Methods:  Seventy-five patients, 42 male and 33 female, with nasal polyposis were examined for total serum IgE, specific serum IgE and reaction to skin test for differentiating allergic from non-allergic participants in Rasoul Akram Hospital during 2010. To determine the possible correlation of allergic reactions in the upper respiratory tract and nasal polyposis, cytokine gene expression was evaluated on the extracted RNA by RT-PCR. The data were analyzed by using c², independent t-test, correlation and Receiver operating characteristic (ROC) curve.
Results:  The mean age of participants was 38 years (18-81 years). IFN-γ and IL-4 gene expressions were more prevalent in allergic than non-allergic individuals (IFN-γ: 39.5% vs. 14.2%, P=0.3 and IL-4: 44.7% vs. 18.9%, P=0.02, respectively). IL-10 and IL-12 (P35 and P40 fractions) genes were not significantly different between the two groups. IL-10 and IL-12 (P35, P40) genes did not differ significantly either.
Conclusion: This research suggests that overproduction of cytokines and an imbalance of Th1 and Th2 cell production may play an important role in the pathophysiology of allergic or non-allergic nasal polyp formation. Thus, although nasal polyposis is a multifactorial disease with several different etiological factors, chronic persistent inflammation is undoubtedly a major factor irrespective of the etiology.