While several new diagnostic tests are changing the dry eye disease (DED) diagnostic paradigm, many clinicians still rely on a conglomeration of signs and symptoms to identify the condition. In an effort to develop a more objective method, researchers recently examined HLA-DR (an antigen at work in graft rejection and other immune reactions) expression in conjunctival cells, a minimally invasive biomarker, as an alternative.

The team found that the distribution of HLA-DR expression in conjunctival cells reflects the heterogeneity of the disease; the new work was performed in Dry Eye Assessment and Management (DREAM) study participants.

A total of 527 DREAM study participants completed the Ocular Surface Disease Index questionnaire. Clinicians then evaluated tear volume, tear break-up time and corneal and conjunctival staining. They assessed conjunctival impression cytology samples for HLA-DR expression in total cells, epithelial cells and white blood cells (categorized based on the percent) and evaluated associations with signs and symptoms.

The investigators discovered that the HLA-DR expression varied considerably across samples—more than 40% of patients had <5% HLA-DR expression positive cells in total and epithelial cells and less than 23% had <5% in white blood cells. They note that higher HLA-DR expression was associated with greater conjunctival staining in total cells and epithelial cells as well as higher corneal staining in total cells. They add that higher HLA-DR expression did not correlate with signs in white blood cells or symptoms in any of the cells.

They note that the high percentage of samples with HLA-DR expression positive cells indicates that it may not be a sensitive marker for DED in all patients.

Although the biomarker may not be useful for identifying DED in all patients, the high percentage of HLA-DR expression in epithelial cells specifically suggests it may be a useful tool for identifying those prone to epithelial disease and in need of a different therapy approach, the researchers concluded.