Monocyte chemotactic activity induced by intravitreal endotoxin

Area of Science:

• Ophthalmology
• Immunology
• Cell Biology

Background:

• Anterior uveitis is characterized by cellular infiltrate in the eye.
• Understanding the chemotactic factors in aqueous humor is crucial for clarifying the pathogenesis of anterior uveitis.

Purpose of the Study:

• To identify and characterize the factors in aqueous humor responsible for monocyte migration during induced anterior uveitis in rabbits.

Main Methods:

• Rabbit eyes were injected with Escherichia coli or Salmonella endotoxin (ET) to induce inflammation.
• Aqueous humor was collected at different time points and analyzed for monocyte chemotactic activity using modified Boyden chambers.
• Chromatographic techniques (Sephadex G-75, Cibacron blue) and biochemical assays (chloroform:methanol extraction, radioimmunoassay, HPLC) were employed for factor identification.

Main Results:

• Aqueous humor collected 18-24 hours after ET induced significant monocyte migration.
• The primary chemotactic activity co-eluted with albumin, but serum albumin alone did not induce migration.
• A secondary peak of activity, present in normal aqueous humor, was also identified and partially attributed to lipids, including leukotriene B4.
• Complement C5a was not a major contributor to aqueous chemotactic activity following local ET, unlike in systemic inflammation.

Conclusions:

• Leukocyte migration factors in aqueous humor, distinct from complement C5a, can be characterized.
• These factors, including albumin-associated molecules and lipids, play a role in the cellular infiltrate of anterior uveitis.
• The characterization of these factors offers a potential method for distinguishing subsets of anterior uveitis.