ANALYSIS OF HUMAN TEAR FLUID COMPONENTS, INHIBITING PROTEIN ADHESION TO PLASTIC SURFACES

In a previous paper we reported the presence of components in human te ar fluid that block the interaction of proteins with plastic surfaces, interfering with tear protein ELISA and proposed the term coating inh ibiting activity. The purpose of the study presented here was to furth er analyse these components. Coating inhibitory activity in human refl ex tears was analysed by lectin affinity chromatography, using the aga rose bound lectin Artocarpus integrifolia agglutinin (Jacalin), gel fi ltration, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (S DS-PAGE), blotting and Jacalin staining. For coating inhibitory activi ty assay in experimental tear samples, the binding of the protein Avid in-conjugated horseradish peroxidase to the polystyrene surface of ELI SA micro-titer plate wells, preincubated with the experimental tear sa mples was measured. In addition, tears were incubated with scrapings o f the ELISA plates used in the assay and with six different types of c ontact lenses (two rigid gas permeable and four hydrogel soft contact lenses) for analysis of adsorbed components. Lectin affinity chromatog raphy of tears yielded a Jacalin-binding and a non-Jacalin-binding pre paration, both exhibiting coating inhibitory activity but representing chemically different preparations as observed by SDS-PAGE. After perf orming gel filtration, coating inhibitory activity eluted with similar retention in both preparations. In fractions exhibiting activity, tea r proteins of low molecular weight (< 40 kDa) were detected. Among the se, two Jacalin-binding glycoproteins were detected; a major component of approximately 28 kDa and a somewhat smaller minor component. All l ow molecular weight components were also detected on the scrapings, in cubated with tears. The possibility that coating inhibitory activity i n tears might reside in a component of larger molecular size can howev er not be excluded. The human tear proteins secretory Immunoglobulin A . lactoferrin and lysozyme are not involved in coating inhibition. On one of the two rigid gas permeable contact lenses incubated with the t ears, the 28 kDa glycoprotein was detected. From the data obtained in our study we conclude that coating inhibitory activity in tears seems to be associated with multiple components of low molecular weight. (C) 1996 Academic Press Limited