Effects of Particles as a Mechanical Filler

The effect of cellular debris, and other particulate matter, on the mechanical properties of mucus depends on the strength of the interaction. It has generally been assumed that cells act as a neutral filler, adding relatively little to the viscoelastic properties of mucus in comparison with other sources of variation in mucous gel viscoelasticity. 

Tracheal mucous samples obtained by scraping, for which the eellularity is high, show little variation in viscoelastic properties from samples obtained by more gentle approaches (7). In the referenced study, the cellular contents of the samples of mucus were not measured however, the fraction of cellular debris in the samples obtained by tracheal scraping was probably higher than in those obtained from the eytology brush. In nonpurulent sputum, the nondispersable dry 

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Contributions of Living Particles to the Rheology of Mucus and Its Clearance 

However, neutrophils also release large quantities of proteases, such as elastase and cathepsin G. These proteases are the most potent secretagogues known (39). Not only do they stimulate the output of mucus from secretory cells, but they are also capable of degrading mucous glycoproteins, particularly when the DNA and actin that accompany the mucins in purulent secretions become degraded (40). Thus the net effect of the by-products of infection on mucus s rheology is rather unpredictable. 

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