Evaluation of the In Vitro Uridine Uptake Inhibition Assay in Comparison with the In Vivo Eye Irritation Test as Prescribed by the EEC

Abstract

In vivo eye irritation tests were carried out on 17 substances (mainly solvents) according to the experimental protocols laid down in the European Community legislation on dangerous substances and the OECD Guidelines. Erythema, chemosis, corneal opacity and iritis were observed and evaluated according to the interpretation rules laid down in EEC legislation.

The uridine uptake inhibition assay was carried out on Human Hep G2 cells according to the method of Shopsis & Sathe (1), modified by Dierickx & Martens (2). Inhibition of uridine uptake was expressed as the UI50 (Hep G2 cells, mM).

Comparison of the results of our two studies revealed only a poor relationship between the UI50 values and the mean scores obtained for corneal opacity (Spearman rank correlation; r=0.57, p<0.02). Consideration of just the monoalcohols, together with the ketones and the formamides, gave a good linear correlation between the UI50 (Hep G2 cells) and the <<Se>> (r=0.93). If a UI50 value of 50mM is accepted as a limit for classification of irritancy for the eye, no false positives or false negatives are obtained.

The UI50 can only be used within strictly defined chemical classes, as a first screening method for detecting possible irritants.

Keywords

in vivo eye irritation corneal opacity erythema in vitro assay Hep G2 cells uridine uptake inhibition cytotoxicity

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