Lymphocytes Cut Off Values of Induced Sputum Samples in Healthy and Non-healthy Patients- A Cross Sectional Study

Background: Induced sputum (IS) is a noninvasive methodology for evaluating airway inflammation in a large number of pulmonary diseases, i.e, Asthma, Chronic obstructive pulmonary disease and Interstitial Lung Diseases. Several studies have defined normal values and cut-off points for this technique based on cellular components of IS, such as percentages of eosinophils, neutrophils, macrophages and CD4/CD8 ratio of T cell lymphocytes. However, normal values and cut-off points for lymphocyte percentages indicative of pathology have not yet been established or validated. This component of IS has considerable clinical value. Similar to other constituents of IS, it can provide biological insights into the pathogenesis of respiratory disorders and contribute to establishing the diagnosis and guiding treatment management of a variety of airway diseases.

The purposes of this study are to define normal values and cut-off points of lymphocytes in IS among individuals with respiratory disorders and healthy volunteers, and to verify the current reference values of the percentage of eosinophils, neutrophils and CD4/CD8 ratio in IS.

Methods: A Cross Sectional study which includes a database on up to 900 patients who participated in various studies conducted in the Pulmonary Laboratory of Tel Aviv Sourasky Medical Center between 2005 to 2012 will be established. The study population will include patients diagnosed as having various pulmonary diseases and a group of healthy volunteers who will serve as controls. The cut-off for normal values of lymphocyte, eosinophil and neutrophil percentages and CD4/CD8 ratio in IS will be defined by using ROC curves and evaluating sensitivity and specificity. The comparison of the different values to those in the literature will be done by using the Spearman rank correlation.

The results of this study will provide supplementary information on lymphocyte counts in IS for identifying and treating various respiratory diseases.