Correlation between tear IgE levels and HLA-DR expression by conjunctival cells in allergic and nonallergic chronic conjunctivitis

Background: Chronic conjunctival inflammatory diseases may depend upon vari ous mechanisms. Discriminating allergy from nonspecific inflammation has be come of striking importance for diagnosis and treatment. We investigated co njunctival inflammatory response by comparing two objective biological tool s, tear IgE and HLA-DR expression by conjunctival epithelium. as indirect i ndicators of activation of the Th2 and Th1 subsets, respectively. Methods: Eighty-two patients with chronic conjunctivitis underwent tear IgE measurem ent by an ELISA technique and quantitation of HLA-DR expression in impressi on cytology specimens. Forty-two had direct or indirect clinical indication s of allergic mechanisms, 26 had chronic conjunctivitis without any sign of allergy, and 14 suffered from isolated nonallergic dry eyes. Results: Pati ents clinically considered as allergic only showed positive IgE in 47 of 84 eyes (56%), whereas 21% and 25% of eyes with nonspecific conjunctivitis an d dry eyes respectively were also positive. IgE levels were significantly h igher in the allergic group than in the other two groups. HLA-DR positivity in epithelial cells was found in 28.5%, 48% and 50% of eyes, respectively. HLA-DR expression by epithelial cells was negatively correlated with tear IgE, as most specimens positive to one criterion were negative to the other one (49 eyes DR+, IgE-; 47 eyes DR-, IgE+; only 9 eyes positive to both cr iteria; chi-square: P=0.0001). Conclusion: As IgE synthesis and HLA-DR indu ction may represent indirect indicators of the activation of the Th2 and Th 1 subsets, association of these two simple tests could be interesting for t he routine assessment of the mechanisms of inflammatory ocular surface dise ases.