Methods of sputum processing for cell counts, immunocytochemistry andin situhybridisation

Abstract

The advantages of using selected sputum are: squamous cell contamination is 20% of all recovered cells 4. There is conflicting data as to whether or not differential cell counts (DCCs) differ between the two methods. One study reported a higher percentage of eosinophils in sputum processed by the selection method compared to the entire expectorate 9 but this has not been confirmed in other studies 2, 6, 10. Although, both the selected sputum and the entire expectorate methods have the same ability to distinguish asthmatics or bronchitics from healthy subjects, they are not interchangeable, and, once a technique has been adopted for a given study, it should always be applied.