Plasminogen activator activity and plasminogen independent amidolytic activity in tear fluid from healthy persons and patients with anterior segment inflammation.

Plasminogen activator activity and plasminogen independent amidolytic activity were measured in human tears by a spectrophotometric method using human plasminogen and chromogenic peptide substrate S-2251. This assay is sensitive predominantly to urokinase-like plasminogen activator. Tears were collected with glass capillaries. The activator activity in normal tears was found to be low, 0.06 +/- 0.04 (SD) IU/ml. Elevated levels were measured in the tears of patients with various types of conjunctival and corneal disorders. The affected epithelial cells of the cornea and conjunctiva were suggested to be responsible for the elevated activity. Plasminogen independent amidolytic activity was usually very low except in cases of increased permeability of the conjunctival blood vessels. The procedure is recommended as a useful tool for the study of the pathological changes in the epithelial cells of the cornea and conjunctiva.