Studies of proteinases and their inhibitors in lung secretions.

The study of proteinases and their inhibitors in lung secretions may provide an understanding of the pathogenesis of many chronic lung diseases. However problems arise in the collection and assessment of the samples that leads to variability both within and between subjects. The purpose of the paper is to highlight these problems as well as the methods used to overcome them in secretions obtained from patients with chronic obstructive bronchitis. The results show that between subject variability is high; and may be up to 150% within an individual. Conventional means of reducing variability (standardisation for albumin) may not be appropriate for some proteins, leading to increased variability. The function of inhibitors is probably best expressed as enzyme inhibited/unit of inhibitor though even this shows daily variability within the same individual. An awareness of such variability is necessary for the interpretation of results obtained from patients.