Human tears: normal protein pattern and individual protein determinations in adults.

Proteins in tears are known to be highly heterogeneous. We have tried to take into consideration some of the difficulties encountered in studying tear proteins such as tear collection, the choice of the parameters to be studied, the adequacy of techniques for small sample volumes, etc. Levels of total tear proteins were determined in 101 samples and the electrophoreses were performed. On gel slabs, four major proteins were always found to be present: lactoferrin, lysozyme and two tear specific proteins. Concentrations of some individual proteins, lactoferrin, lysozyme, IgA, IgG and albumin were determined. Comparisons of lactoferrin and lysozyme contents were found to be more reliable when based on total protein rather than on their own concentrations as such.