Inflammation: neutrophils and eosinophils
There are three common clinical characteristics in obstructive pulmonary diseases: airway inflammation, airway obstruction and bronchial hyperresponsiveness (BHR). Chronic inflammation is considered to be mainly eosinophilic and driven by CD4 cells in asthma, while it is neutrophilic and driven by CD8 cells in CoPD (14,15). Nonetheless, noneosinophilic and neutrophilic asthma has been reported too, which displayed resistance in steroids (6,17). Smokers asthmatics have elevated neutrophils in their airways, similar to COPD. Smoking promotes neutrophilic inflammation which in turn causes increased corticosteroid resistance (8,19). On the contrary, eosinophilic inflammation has been observed in some COPD patients and is correlated with greater reversibility of obstruction when steroids are given (20). When randomly selected asthmatics with incomplete reversibility are studied, we can notice elevated neutrophils in their airways and additionally the intensity of neutrophilia is related with the FEvi decline (21-23). Furthermore, it has been already proven from histopathological and other studies that inflammation concerns all airways, large 2 mm in diameter) and small distal (k2 mm in diameter), even the lung tissue, in both COPD and asthma patients