Assessment of serum interleukin 6 level in patients with chronic obstructive pulmonary disease: is it related to disease severity?

Chronic obstructive pulmonary disease (COPD) is a common disease that can be prevented and even treated. It leads to high morbidity and mortality rates. Pro-inflammatory cytokines and oxidative radicals were found to be implicated in COPD pathogenesis. To measure serum level of interleukin 6 (IL-6) in patients with stable COPD and also to detect the relationship of IL-6 levels with COPD severity. A total of 50 patients having stable COPD, in addition to 20 healthy control individuals, were included in the study. History taking and clinical examination, BMI calculation, spirometry (postbronchodilator spirometry in COPD group), and 6-min walk test were done for all patients. Measurement of serum level of IL-6 was done by using the enzyme-linked immunosorbent assay. Serum level of IL-6 showed significantly higher concentrations among patients with COPD compared with healthy individuals [359.87±106.99 and 188.92±77.97 pg/ml, respectively; P <0.001]. An inverse nonsignificant correlation was found between serum level of IL-6 and 6-min walk test distance, forced expiratory volume in the 1 s, forced vital capacity, and maximum expiratory flow 25–75% predicted values. Mean IL-6 level was higher in the patients with severe and very severe COPD (371.75±103.12 pg/ml) compared with those with mild and moderate COPD (336.82±113.72 pg/ ml) ( P =0.291). Serum level of IL-6 showed significant higher concentrations in patients with COPD when compared with control ones, but IL-6 level did not show significant correlation with the disease severity.