Biochemistry and rheology of sputum in asthma.

IN RECENT years there have been many advances in the epidemiology of chronic bronchitis and in the immunology and treatment of asthma but scant attention has been paid to a factor common to both diseases-the production of mucoid sputum. It is still not known why some men can smoke heavily all their lives without developing the hypersecretion of mucus which characterizes simple chronic bronchitis, nor why some patients with asthma have a profuse bronchorrhoea. Nor is it known why the hypersecretory state, once established, is so often, but not always, complicated by bacterial infection. Much has been written of the viscosity of sputum which does not stand up to measurement by modem techniques and with little knowledge of the part it plays in obstructive airways disease.