ABSTRACT
Sputum cytology has been an important part of assessment for tuberculosis and cancer for decades, but it is only over the past 15 years that this method has been used extensively for the study of non-infectious inflammatory lung diseases. Initially, sputum was examined for the presence of eosinophils on stained smears. However, assessment of smears is difficult and counts unreliable because of the inhomogeneous distribution of cells entrapped in mucus (Figure 2.1). The introduction of reducing agents such as dithiothreitol (DTT) or dithioerythritol (DTE) to disperse mucus and release trapped cells has made it possible to prepare homogeneous cell suspensions and an ‘imprint’ of these cells using a cytocentrifuge to generate cytospins with a monolayer of cells. This approach has made quantification and characterization of inflammatory cells in the airways reliable.
