The presence of T-lymphocyte subpopulations (CD4 and CD8) in pterygia: Evaluation of the inflammatory response

Introduction: The aim of our study was to confirm the presence of inflammatory T-lymphocyte subpopulations (CD4 and CD8) in pterygium specimens with regards to clinical severity. Additionally, we examined the effect of topical anti-inflammatory agents on the presence of T-lymphocyte subpopulations. Methods: Pterygia from nineteen eyes of nineteen patients who underwent surgical excision at Duke University, North Carolina, were included in this study. Normal conjunctiva from one patient was included as a control. Pterygia were pre-operatively graded as mild, moderate or severe based on objective signs of inflammation. Immunohistochemical staining for both CD4 and CD8 subpopulations of T lymphocytes was performed. Distribution of lymphocytes within the epithelium and substantia propria was graded by a masked observer on the following scale: 0 (none/rare), 1+ (mild), 2+ (moderate), or 3+ severe. Statistical analysis was performed using the Fisher exact test and Chi-square test. Results: A total of 16 (84%) pterygia specimens stained for T lymphocytes displayed approximately equal CD4 and CD8 infiltration of both the epithelium and the substantia propria. The majority of CD4 and CD8 lymphocytes were located in aggregates in the epithelium and upper substantia propria. The control specimen contained scant evidence of lymphocytic infiltration. There was no significant difference in the amount of lymphocytic infiltration between mild, moderate or severe pterygia. There was also no significant difference in lymphocytic infiltration between patients with (n=8) or without (n=11) a history of topical anti-inflammatory use. Conclusion: The presence of CD4 and CD8 lymphocytes was confirmed in pterygia. There was no significant difference in lymphocytic infiltrate in patients with or without prior topical anti-inflammatory use. Based on these findings, topical immunomodulators may have an adjunctive role in the treatment of pterygia.