The dominant human conjunctival epithelial CD8αβ+ T cell population is maintained with age but the number of CD4+ T cells increases

Abstract

The conjunctiva is a highly specialized ocular mucosal surface that, like other mucosa, houses a number of leukocyte populations. These leukocytes have been implicated in age-related inflammatory diseases such as dry-eye, but their phenotypic characteristics remain largely undetermined. Existing literature provides rudimentary data from predominantly immunohistochemical analyses of tissue sections, prohibiting detailed and longitudinal examination of these cells in health and disease. Using recovered cells from ocular surface impression cytology and flow cytometry, we examined the frequency of leukocyte subsets in human conjunctival epithelium and how this alters with age. Of the total CD45+ leukocyte population within the conjunctival epithelium, 87% [32–99] (median) [range] comprised lymphocytes, with 69% [47–90] identified as CD3 + CD56- T cells. In contrast to peripheral blood, the dominant conjunctival epithelial population was TCRαβ + CD8αβ + (80% [37–100]) with only 10% [0-56%] CD4+ cells. Whilst a significant increase in the CD4+ population was seen with age (r = 0.5; p < 0.01) the CD8+ population remained unchanged, resulting in an increase in the CD4:CD8 ratio (r = 0.5;p < 0.01). IFNγ expression was detectable in 18% [14–48] of conjunctival CD4+ T cells and this was significantly higher among older individuals (<35 years, 7[4–39] vs. >65 years, 43[20–145]; p < 0.05). The elevation of CD4+ cells highlights a potentially important age-related alteration in the conjunctival intra-epithelial leukocyte population, which may account for the vulnerability of the aging ocular surface to disease.

Tissue resident memory T cells in the human conjunctiva and immune signatures in human dry eye disease

“…1C). Our results are consistent with an earlier study, which reported a preponderance of CD8 + T EM cells in the ocular surfaces of a cohort of human volunteers in the UK13.…”

“…The mucosa covering the avascular corneal surface at the visual axis contains mainly myeloid and dendritic cells, while the conjunctiva over the remainder of the ocular surface also contains lymphatics, diffuse and aggregated lymphocytes1314. While T cell subsets have been described in the conjunctiva13, the relative proportions of T RM and recirculating T cells at this barrier surface have not been studied in humans or animal models. Such information could provide insights into ocular surface inflammation.…”

Elevation of Conjunctival Epithelial CD45INTCD11b+CD16+CD14−Neutrophils in Ocular Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

“…8 While these studies did not examine ocular disease, earlier studies have identified corneal CD8 þ T cells with epithelial vacuolation in a patient with TEN, 9 and a predominant CD8 þ T-cell population in healthy human conjunctival epithelium. 12,25 In our current study, we found that conjunctival CD8 þ and NK þ populations were not significantly elevated in SJS-TEN compared with healthy controls and this remained unchanged over time. This discrepancy might be explained by the fact that SJS-TENinduced damage is thought to be mediated by granulysin rather than the extent of cytotoxic cellular infiltrate.…”

“…11,12 Briefly, conjunctival cells were collected from the superior bulbar conjunctiva with autoclaved synthetic membranes (Supor 200; Pall Corporation) divided into two semicircles (measuring 13 3 6.5 mm 2 each). 11 Conjunctival OSIC was performed with four semicircle membranes per eye and before the application of topical fluorescein drops for clinical examination.…”

“…12 Multicolor cytometry compensation was performed using cells or compensation beads individually stained with each fluorochrome conjugatedantibody in order to circumvent spectral overlap by adjusting for false-positives from other fluorochromes. Analysis was undertaken with acquisition and analysis software (Summit 4.3 for Windows; Beckman Coulter).…”