en ایمنی شناسی Immunology پژوهشي Research <p><b>Background and Aims:</b> Chronic obstructive pulmonary disease (COPD) is a kind of pulmonary diseases characterized by chronic obstruction of lung that is in the form of a diffuse narrowing of airways resulting in air flow resistance. Alpha-1 antitrypsin (AAT) deficiency is genetically relatively common risk factor in patients with COPD throughout the world and the exact cause of its prevalence is unknown. We therefore performed a study to determine the frequency of AAT deficiency in patients with severe COPD compared to the healthy controls.<br> <b>Materials and Methods:</b> In this cross-sectional case control study, AAT serum level in 60 patients with severe COPD for whom the history and spirometry test with FEV1<50% had been confirmed based on gold criteria as well as 60 healthy controls, were tested using commercial kit and nephelometry method.<br> <b>Results:</b> The lowest serum levels of AAT measured in patients was <0.349 g/l and the highest was 3.099 g/l. These were obtained in healthy subjects as 1.180 g/l and 4.195 g/l respectively. Out of 60 patients, 4 (6.7%) had partial deficiency of AAT (AAT<1 g/l) and 6 (10%) had definite shortage of AAT (AAT<0.5 g/l). In healthy subjects, we did not find any definite and relative lack of AAT. The comparison of results obtained from these two groups indicated a significant difference between frequency of AAT (P=0.001).<br> <b>Conclusions:</b> Our findings revealed the frequency of AAT deficiency, as a factor involved in COPD disease, to be 10% and can be the reason for the high prevalence and severity of COPD in Zahedan city.</p> Alph-1-antitrypsin, COPD, Zahedan 112 120 http://ijml.ssu.ac.ir/browse.php?a_code=A-10-1-23&slc_lang=en&sid=1 Nezarali Moulaei No Internal Medicine Department, Research Centre for Tropical and Infectious Diseases, Zahedan University of Medical Sciences, Zahedan, Iran. Hossein Ali Khazaei Yes Immunology and Hematology Department, Clinical Immunology Research Center, Zahedan University of Medical Sciences, Zahedan, Iran. Vida Pejman No Zahedan University of Medical Sciences, Zahedan, Iran.