Abstract
Purpose :
T cell infiltration of the ocular surface is commonly only associated with inflammation and diseases such as dry eye. Neutrophils are well known to populate the closed eye during eyelid closure, and have been shown to signal the adaptive immune response in other organ systems. The purpose of this investigation was to catalogue and phenotype various leukocytes of the closed eye.
Methods :
Eleven healthy participants were recruited and were trained to wash the ocular surface with phosphate buffered saline for at-home self-collection of tear film leukocytes following a full night of sleep. Cells were isolated and counted and were incubated with fluorescently-labeled antibodies against CD45, CD14, CD15, CD16, CD11b to identify neutrophils and monocytes. Antibodies against CD45, CD3, CD4, CD8, CD196, and CD161 were used to identify T cells. A Becton Dickinson (BD; San Jose, CA) proprietary fixable viability stain was used to exclude dead cells from analysis. A BD LSR II flow cytometer was used for all analysis.
Results :
Neutrophils were the most dominant of all cell populations, representing roughly 58% of all leukocytes. Monocytes were not readily observed, representing only a small portion of cells (<2%). Both CD4+ and CD8+ T cells were found in the ocular surface eyewash after a full night of sleep. CD4+ were more abundant, representing approximately 7% of the total leukocyte population, while CD8+ cells were roughly 1.5% of the total leukocyte population. Finally, Th17 cells, as identified as being CD196+CD161+ represented, on average, 20% of the total CD4+ T cells.
Conclusions :
This investigation demonstrated T cell surveillance of the ocular surface, during sleep. Combined neutrophil and T cell infiltration suggests that closed eye homeostasis is complex, and future studies seek to identify the mechanisms of leukocyte interaction and activation, and ultimately determine how dysregulation may contribute to disease.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.