Complement inhibitors in tears of different species

Area of Science:

• Immunology
• Comparative Biology
• Biochemistry

Background:

• The complement system is a crucial part of innate immunity.
• Tear film plays a role in ocular surface protection.
• The presence and function of complement inhibitors in tears are not well understood.

Purpose of the Study:

• To investigate the presence and activity of complement inhibitors in the tears of various animal species.
• To characterize the nature and mechanism of action of these tear-derived complement inhibitors, particularly in rabbits.

Main Methods:

• Collection and analysis of tears from multiple species (rat, mouse, goat, guinea pig, rabbit, rhesus monkey, chicken, cat, human).
• Assay of anti-complementary activity in collected tear samples.
• Biochemical characterization of inhibitors in rabbit tears using gel-filtration and SDS-PAGE.
• Mechanistic studies to determine the point of inhibition in the complement cascade.

Main Results:

• Rat and mouse tears exhibited strong anti-complementary activity.
• Goat, guinea pig, rabbit, and rhesus monkey tears showed inhibition levels comparable to human tears.
• Chicken and cat tears displayed weak anti-complementary activity.
• A small protein (approx. 20,000 daltons) was implicated in rabbit tear anti-complementary activity.
• Inhibition in rabbit tears occurs after the formation of the EAC14 intermediate.

Conclusions:

• Tears from various species contain inhibitors of the complement system.
• A specific protein in rabbit tears contributes to anti-complementary effects.
• These findings facilitate further research into the physiological roles of tear film complement inhibitors.