Changes in lactoferrin and other proteins in a case of chronic recurrent parotitis

Parotid fluid samples from an individual with chronic recurring parotitis were collected during acute exacerbation and then at various stages of recovery. The samples were serially examined for: (a) lactoferrin (Lf) and lysozyme concentration, (b) concentration of IgA, IgG, IgM, albumin and transferrin, (c) amylase activity and protein pattern on acrylamide disc gel electrophoresis, (d) myeloperoxidase (MPO). The most dramatic protein changes occurred during the initial exacerbation with a more than 20‐fold increase in total protein, because of an influx of serum proteins, Lf, lysozyme and MPO. By 5 days following the exacerbation the protein concentration was only two times normal; serum proteins were still evident but intrinsic salivary proteins were the major components; Lf, and to a lesser extent lysozyme, were still elevated; MPO was no longer detected. By day 11, total protein concentration was nearly normal; only albumin and Lf were modestly elevated. The elevation in Lf concentration during this period was accompanied by a shift in its apparent molecular weight. A polymeric form of Lf, observed during the acute stage, changed to what appeared to be a dimeric and then a monomeric form as the inflammatory process subsided. At day 79, parotid fluid chemistry was normal in almost all respects; only a slight elevation in albumin suggested any residual pathology.