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

Chronic conjunctival inflammatory diseases may depend upon various mechanisms. Discriminating allergy from nonspecific inflammation has become of striking importance for diagnosis and treatment. We investigated conjunctival inflammatory response by comparing two objective biological tools, tear IgE and HLA-DR expression by conjunctival epithelium, as indirect indicators of activation of the Th2 and Th1 subsets, respectively. Eighty-two patients with chronic conjunctivitis underwent tear IgE measurement by an ELISA technique and quantitation of HLA-DR expression in impression cytology specimens. Forty-two had direct or indirect clinical indications of allergic mechanisms, 26 had chronic conjunctivitis without any sign of allergy, and 14 suffered from isolated nonallergic dry eyes. Patients clinically considered as allergic only showed positive IgE in 47 of 84 eyes (56%), whereas 21% and 25% of eyes with nonspecific conjunctivitis and dry eyes respectively were also positive. IgE levels were significantly higher 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 criteria; chi-square: P = 0.0001). As IgE synthesis and HLA-DR induction may represent indirect indicators of the activation of the Th2 and Th1 subsets, association of these two simple tests could be interesting for the routine assessment of the mechanisms of inflammatory ocular surface diseases.