Clinical Usefulness of Simultaneous Measurement of the Tear Levels of CCL17, CCL24, and IL-16 for the Biomarkers of Allergic Conjunctival Disorders

Purpose: This study investigated the clinical usefulness of a multiple tear cytokine/chemokine test by simultaneously determining tear levels of CC chemokine ligand 17 (CCL17)/thymus and activation-regulated chemokine (TARC), CCL24/eotaxin-2, and interleukin-16 (IL-16) for assessing acute and chronic allergic inflammation in allergic conjunctival disorders (ACDs). Subjects and Methods: This study included 37 patients with ACD and 11 healthy adults (controls). Patients with ACDs were divided into the following three groups; patients with allergic conjunctivitis (AC group, n = 17), patients with atopic keratoconjunctivitis (AKC group, n = 6), and patients with vernal keratoconjunctivitis (VKC group, n = 14). Tear samples were collected using the Schirmer I method with a filter paper. Tear levels of CCL17/TARC, CCL24/eotaxin-2, and IL-16 were determined by performing a magnetic bead assay (tear cytokine/chemokine test). Tear levels of eosinophil cationic protein (ECP) were determined by performing enzyme immunoassay. In patients with AC, clinical scores of objective findings and results of the tear cytokine/chemokine test at baseline were compared with those at 7 days after treatment with the histamine H-1 receptor antagonist (epinastine) ophthalmic solution. Results: Tear positive rates of CCL17/TARC, CCL24/eotaxin-2, and IL-16 were higher in patients with AC, AKC, and VKC compared with controls. Tear levels of CCL17/TARC, CCL24/eotaxin-2, and IL-16 in patients with AKC and VKC were significantly higher than those in patients with AC. Moreover, tear levels of IL-16 in patients with AC that showed improvement of their clinical score by treatment with epinastine ophthalmic solution decreased significantly after 7 days of the treatment compared with those at baseline. In patients with AKC and VKC, a significant correlation was observed between the tear levels of CCL24/eotaxin-2 and ECP. Conclusion: Simultaneous measurement of the tear levels of CCL17/TARC, CCL24/eotaxin-2, and IL-16 may be a useful test for assessing acute and chronic allergic inflammation in ACDs.