Evaluation of Interleukin-17 and Interleukin-23 in Pterygium: Immunohistochemistry Study

PURPOSE: To compare the interleukin-17 (IL-17) and interleukin-23 (IL-23) positive cell counts between pterygium and normal conjunctiva.

DESIGN: A case-control study.

METHODS: This study received ethical approval (NMRR Research ID 23957) and informed consent was obtained from all participants. It involved 20 participants with 20 samples of pterygium and 20 samples of normal conjunctiva that were obtained from the same eye of each participant. All the participants underwent history taking, slit lamp examination, and pterygium excision surgery. Both samples underwent immunohistochemistry procedure. Pretreatment procedure was conducted using heat-induced epitope retrieval with PT link, subsequently followed by EnVision FLEX staining procedure and incubation with anti‒IL-17 antibody and anti‒IL-23 antibody. Slides were examined in high-power fields (400x) for both samples in 3 different fields. Total positive stained cell counts in all 3 fields with IL-17 and IL-23 between pterygium and normal conjunctiva were analyzed by using Wilcoxon signed rank test.

RESULTS: IL-17 positive cell counts for normal conjunctiva showed mean 196.10 ± 80.487 but for pterygium was 331.10 ± 108.416. As for IL-23, the mean for positive cell counts for normal conjunctiva was 62.10 ± 33.462 and IL-23 positive cell counts for pterygium showed mean 102.95 ± 41.378. Both IL-17 and IL-23 were significantly increased in pterygium compared with normal conjunctiva (P < 0.001).

CONCLUSIONS: Both IL-17 and IL-23 were found to be significantly higher in the pterygium group than in the normal conjunctiva group with P < 0.001 by Wilcoxon signed rank test.