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

Area of Science:

• Ophthalmology
• Biochemistry
• Proteomics

Background:

• Tear proteins exhibit significant heterogeneity.
• Studying tear proteins presents challenges in collection and analysis of small sample volumes.
• Standardized methods are needed for reliable tear protein quantification.

Purpose of the Study:

• To address challenges in tear protein analysis.
• To determine reliable methods for quantifying individual tear proteins.
• To investigate the relationship between individual protein concentrations and total protein levels.

Main Methods:

• Collected 101 tear samples.
• Determined total tear protein levels.
• Performed gel electrophoresis to identify major tear proteins.
• Quantified specific proteins including lactoferrin, lysozyme, IgA, IgG, and albumin.

Main Results:

• Identified four major proteins consistently present: lactoferrin, lysozyme, and two tear-specific proteins.
• Lactoferrin and lysozyme concentrations were more reliably compared when normalized to total protein.
• Individual protein concentrations varied, highlighting the importance of relative quantification.

Conclusions:

• Relative quantification of tear proteins, particularly lactoferrin and lysozyme, against total protein improves reliability.
• The findings offer a more robust approach to tear protein analysis.
• This method aids in understanding tear composition and its clinical implications.