Tolerance is dependent on complement C3 fragment iC3b binding to antigen-presenting cells.

Area of Science:

• Immunology
• Ophthalmology
• Complement System Biology

Background:

• Systemic tolerance can be induced by introducing antigens into immune-privileged sites.
• The role of the complement system in this process remains incompletely understood.

Purpose of the Study:

• To investigate the role of complement in inducing immune tolerance after intraocular antigen injection.
• To identify specific complement components involved in tolerance induction.

Main Methods:

• Intraocular antigen injection in a model system.
• Analysis of complement activation products and their receptors.
• Measurement of cytokine production (transforming growth factor-beta2 and interleukin-10).

Main Results:

• Antigen-specific tolerance induction was dependent on a complement activation product.
• Ligation of complement C3 activation product iC3b to complement receptor type 3 on antigen-presenting cells was critical.
• This interaction led to sequential production of transforming growth factor-beta2 and interleukin-10.

Conclusions:

• The complement system, specifically the iC3b/complement receptor type 3 pathway, plays a crucial role in inducing antigen-specific tolerance after intraocular injection.
• The findings highlight the importance of transforming growth factor-beta2 and interleukin-10 in this tolerance mechanism.
• These insights may inform strategies for neonatal and acquired tolerance development.