Purchase this article with an account.
S. Zhang, R.N. Borazjani, J.C. Salamone, D.G. Ahearn, S.A. Crow, Jr., G.E. Pierce; In vitro Effects of Lactoferrin and Other Tear Proteins on Lysozyme Deposition and Activity on Silicone Hydrogel Contact Lenses . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2415.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Earlier studies have demonstrated that lysozyme was adsorbed and absorbed to an etafilcon A HEMA–type traditional contact lens at about a ten– fold greater concentration than to a balafilcon A silicone hydrogel lens. Enzyme activities on the surfaces of both lenses were similar, but activity on the surface of the HEMA lens was replenished from lysozyme absorbed into the matix after saline extraction. Lysozyme on the lens surface showed significant lysis of Micrococcus luteus (Zhang et al.2005. Contact Lens and Anterior Eye 28:113–119). It is unclear if lysozyme alone in buffer behaves differently from lysozyme in the presence of lactoferrin and various other proteins. The objective of this study was to determine the relative activities of mixed tear proteins (lysozyme mixed with albumin, mucin or lactoferrin) when deposited on different types of silicone hydrogel lenses.
Unworn etafilcon A lenses and silicone hydrogel lenses (balafilcon A, lotrafilcon A, lotrafilcon B, galyfilcon A and senofilcon A) were soaked in lysozyme (500 µg/ml) alone or in lysozyme combined with lactoferrin, albumin or mucin for time periods up to 22 h. The activity and amount of lysozyme deposited on lenses were determined with a micrococcyl assay and a micro–BCA assay.
Lysozyme in combination with lactoferrin gave enhanced lysis of cells of M. luteus suspended in buffer versus lysozyme alone. The adsorption and absorption of lysozyme and of the lysozyme–lactoferrin combination was reduced significantly to the various silicone hydrogel lenses versus the HEMA lens. This combination did not show enhanced lysis of M. luteus over that obtained with lysozyme alone. The addition of albumin and mucin to lysozyme did not significantly alter the lytic effects on M. luteus.
In vitro tests indicated that currently available silicone hydrogel contact lenses, including extended–wear and daily–wear lenses of different water content, sorb significantly reduced amount of lysozyme versus the etafilcon A lens. Moreover, the residual enzymatic activity of lysozyme deposited on the surfaces of the lenses was not markedly changed in the presence of other proteins found in tears.
This PDF is available to Subscribers Only