Abstract
Eosinophils, a distinct group of white blood cells, were named by Paul Ehrlich in the late 19th century based on the affinity of their specific granules for the synthetic acidic dye eosin. Since their discovery, their occurrence in the body has been associated with bronchial asthma and helminthiasis.
Today, we already know that their deregulated activity, associated with their peripheral blood count blood above the normal limit, is linked to a number of other diseases, collectively referred to as eosinophilic syndromes, one of them being eosinophilic bronchial asthma. It is estimated that in about half of eosinophilic syndrome cases, the respiratory tract is involved and, conversely, in about half of bronchial asthma cases, eosinophilic inflammation is revealed based on the number of eosinophils in induced sputum.
Therefore, the peripheral blood eosinophil count should be an integral part of the basic examination of patients and broad differential diagnosis of lung diseases, including asthma. It should be performed repeatedly, always at the time of diagnosis and, ideally, before the initiation of any anti-inflammatory therapy, as well as during exacerbations of the underlying disease.
If pulse systemic corticosteroids have already been administered, the eosinophil count should be performed sufficiently long after their discontinuation. Information about peripheral blood eosinophilia should always be an impetus for a careful examination of the patient in order to confirm or rule out its primary or secondary causes as well as possible organ involvement associated with eosinophilia.
In bronchial asthma, confirming the high eosinophil count is crucial not only for classification of the inflammatory phenotype of asthma, but also for other possible therapeutic steps, including biological treatment for severe asthma.