To compare the protein composition of tear fluid obtained from patients with primary Sjögren's syndrome, patients with other connective tissue diseases and control individuals.
SDS polyacrylamide gel electrophoresis followed by staining with Coomassie blue and Western blotting.
Comparison revealed the presence of a characteristic difference in the ratio of intensity between the albumin and lactoferrin bands. An albumin:lactoferrin ratio above 2:1 was significantly more common in patients with primary Sjögren's syndrome than in patients with other connective tissue diseases or the controls.
An albumin:lactoferrin ratio above 2:1 may therefore prove of use when diagnosing 1(0)SS. Used as a test, its sensitivity was 67% and its specificity 100%.