White blood cells are often prevalent in dry eye disease, but little research has explored the phenotype and extent of activation of these cells. Researchers from the University of Alabama at Birmingham shed some light on this in a recent study of 12 patients with DED and a control group.

The DED group was trained to self-collect closed-eye tear samples immediately upon awakening. The researchers then isolated tear leukocytes and collected peripheral blood, which was stained with a panel of fluorescently labeled antibodies to determine the activation phenotype of neutrophils.

The researchers found that the DED and control groups had similar numbers of tear leukocytes recovered at awakening. However, they reported that tear neutrophils from DED patients had increased expression, as documented by a chemical marker associated with secondary granule degranulation. The DED group also had a higher proportion of monocytes compared with the control group. Additionally, DED patients had significantly higher extracellular matrix metalloproteinase-9 and elevated neutrophil elastase, but the latter wasn’t statistically significant.

The researchers concluded that increased inflammation was evident in the closed-eye tears of DED patients, and that neutrophils may be a potential source of pathogenic species in dry eye, but further research is necessary to determine any diagnostic potential from obtaining closed-eye tear samples.