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Tear Film Chemistry & Diagnostics

Friday, September 21, 2018


A paper published in Experimental Eye Research addresses the viability of establishing measurable protein concentrations in tears.

This is not at all surprising to those of us who have passionately studied tear chemistry for decades. We can only hope that Mike Touch's spirit is somewhere celebrating this new paper. For those of you who might not know, we all stand on the shoulders of Mike's unwavering 25-year commitment to tear chemistry diagnostics, particularly where lactoferrin is concerned.

Lactoferrin is found in the tears, the saliva and the mucosal secretions. Early investigators believed that lactoferrin acts primarily by binding iron (as do most antibiotics), thus preventing bacteria from dividing and multiplying. However, newer research has demonstrated that lactoferrin actually does much more than merely steal iron away from pathogenic bacteria.

An interesting discovery was that bovine lactoferrin becomes much more active as a bactericidal after it has been digested by pepsin and acid proteases. Undergoing digestion by the protease pepsin in the stomach liberates the peptide lactoferricin B.

Lactoferricin B, as is true of lactoferrin, plays a role in supporting and modulating the immune system. It has shown extremely strong activity against both Gram-negative and Gram-positive bacteria. In other words, exposure to digestion in the stomach possibly increases the potency of lactoferrin via the liberation of lactoferricin B.

Lactoferrin has been shown to be active in both in vitro and in vivo tests against a large number of pathogens, including Staphylococcus epidermidis, Streptococcus pneumoniae, and Candida albicans.

Lacoferrin has a specific binding capacity for Escherichia coli (E. coli) bacteria such as are often found in human intestines. It is believed to promote the growth of Bifidobacterium, which also helps maintain a healthy intestinal digestive and immune system.

Natural killer cell neutrophils also stimulate aqueous tear film lactoferrin production, which produces tears that are at the ready to deal with unwanted pathogens.

Ellen Troyer, with Spencer Thornton, MD, David Amess and the Biosyntrx staff


 


PEARL

Lactoferrin, also known as lactotransferrin, is a multifunctional protein of the transferrin family. Lactoferrin is a globular glycoprotein with a molecular mass of about 80 kDa that is widely represented in various secretory fluids, such as milk, saliva, tears, and nasal, and vaginal secretions.

Thanks to advancing technology, a device called TearScan 270 MicroAssay System that measures tear film lactoferrin is being used in more and more eye care physician offices, resulting in improved and more efficient patient care.