Inhibitory activity of soluble material from sheep eosinophils for sheep complement

Area of Science:

• Immunology
• Biochemistry

Background:

• The alternative pathway of complement activation is crucial in immune responses.
• Eosinophils play a role in immune regulation, but their specific inhibitory functions are not fully understood.

Purpose of the Study:

• To investigate the inhibitory effects of sheep eosinophil extracts on complement activation.
• To identify the components within eosinophil extracts responsible for this inhibition.

Main Methods:

• Sheep eosinophils were frozen and thawed, and extracts were prepared via sonication.
• Extracts were fractionated using Sephadex G-50 chromatography.
• The inhibitory activity of fractions on the alternative pathway of sheep complement-mediated lysis of antibody-sensitized human erythrocytes was assessed.

Main Results:

• Soluble material from sheep eosinophils and their granules inhibited the alternative activation pathway of sheep complement.
• The inhibitory activity was concentrated in the void volume fraction of sonicated extracts.
• This active fraction co-eluted with eosinophil peroxidase activity.

Conclusions:

• Sheep eosinophils contain soluble factors that can inhibit the alternative complement activation pathway.
• Eosinophil peroxidase is likely associated with, or responsible for, this complement inhibitory activity.