Expression of ICAM-1 on conjunctival epithelium and ECP in tears and serum from children with allergic conjunctivitis

Conjunctival eosinophilia may be considered to be an indicator of conjunctival allergic disease. The absence of eosinophils on conjunctival scraping, however, cannot rule out the diagnosis of allergic conjunctivitis because eosinophil infiltration may be deeper in conjunctival tissue. Eosinophil cationic protein (ECP) is a toxic product secreted by activated eosinophil as a marker of eosinophil activation. Eosinophil cationic protein concentrations in body fluids correlate with the severity of some allergic diseases. ICAM-1 promotes adhesion of leukocytes to epithelium, endothelium, and upregulates inflammation. Expression of adhesion can be modified by many extracellular and intracellular variables such as proinflammatory cytokines, extracellular matrix proteins, and viral infection. We investigated whether local eosinophils are only activated in conjunctival epithelium or circulating activated eosinophils are involved in peripheral blood during allergic reaction of the eye. We also demonstrated the possible expression of ICAM-1 on epithelial cells from conjunctival scraping and compared them with soluble ICAM-1 values of serum and tears in children with allergic conjunctivitis and healthy children. Seventeen subjects were selected on the basis of clinical manifestations, history, skin prick test, and total serum IgE. A microcapillary tube was used to collect the tears from the inner canthus. Conjunctival epithelia were obtained by scraping the upper tarsal conjunctiva. The level of ECP was measured by the CAP system, soluble ICAM-1 was measured by ELISA, and ICAM-1 on conjunctival epithelial cells were expressed by the avidine-biotin peroxide complex procedure. Serum IgE and the eosinophil count were increased in 10 out of 17 patients, positive skin prick tests were positive in 11 patients Dermatophagoides pternyssinus; 9, Dermatophagoides farinae: 8), and eosinophilia in conjunctival epithelium was in 11 patients (4 patients: >3/HPF, 7 patients: 1-3/HPF). The ECP levels in tears were significantly increased in the patient group (12.0 ± 8.0 versus 3.9 ± 3.8 μg/mL, P = .01), but not in serum (52.5 ± 43.1 versus 28.3 ± 25.9 μg/mL). There is significant correlation between the eosinophil count in peripheral blood and on conjunctival epithelium ( P = .007, r = .62; n = 25). The ICAM-1 expression score on conjunctival epithelial cells was significantly different between the patient group and controls (patient group: 1.77 ± 1.25 versus control: 0.13 ± 0.35 ng/