Cytological examination of sputum in relation to its macroscopic purulence.

Investigations into the bacteriology of chronic bronchitis (May, 1953a and b) have shown that purulent sputum usually contains one or more pathogens and that such a sputum can be rendered mucoid, at any rate temporarily, when the patient is treated with the appropriate antibiotic. Subsequent studies (May, 1954) included patients diagnosed clinically as infected asthma, and the macroscopical appearance of the sputumfrom these patients suggested the presence of pus, although in many instances pathogenic organisms could not be demonstrated and chemotherapy failed to alter its appearance. Examination of the cellular contents of such sputa showed that in most cases the " pus " consisted mainly of eosinophils. As a result of these observations investigations have been undertaken to develop a satisfactory method for the cytological examination of sputum, for the distinction between neutrophil and eosinophil "pus " is clearly of great importance. The examination of single smears of sputum for eosinophils is of little value, since the distribution of these cells is often irregular (see below). The sputum must, therefore, be homogenized in order to obtain an even suspension of cells before the film is made. Pancreatin used for this purpose (Rawlins, 1953) does not cause cellular destruction. This paper describes a method whereby the total number of cells per unit volume of sputum can be estimated as well as the relative number of eosinophils.