In vitro restructuring effect of human airway immunoglobulins A and lysozyme on airway secretions.

Abstract

The in vitro effects of different pure proteins: IgA, IgM and human airway lysozyme (HAL) on rheological and transport properties of airway secretions from patients with chronic bronchitis, were studied. The proteins were added to the reconstituted sputum samples in concentrations within the range present in sputa (IgA: 4% HAL: 1% and IgM: 0.5%). A significant (p less than 0.05) positive increase in apparent viscosity and in elastic modulus was observed after adding IgA or HAL. This suggests that these two secretory proteins contribute to the viscoelastic properties of airway secretions and may act as restructuring molecules. After protein overload of the sputum samples, opposite changes in mucociliary transport rate were observed according to whether the initial values of protein concentration and rheology were abnormally low or high. These results suggest that, as for mucus rheology, there is an intermediate range of IgA and HAL optimal for mucociliary transport rate.