Peripheral induction of tolerance by retinal antigen expression

Area of Science:

• Immunology
• Neuroscience
• Ophthalmology

Background:

• The role of peripheral tissue-specific antigens in central nervous system (CNS) tolerance is not fully understood.
• Investigating how peripheral antigen expression influences immune responses is critical for understanding autoimmune diseases.

Purpose of the Study:

• To determine if peripheral expression of a tissue-specific antigen, beta-galactosidase (beta gal), in the retina can induce immune tolerance.
• To investigate the role of regulatory T cells in this tolerance mechanism.

Main Methods:

• Utilized transgenic mice expressing beta-galactosidase (beta gal) in retinal photoreceptor cells.
• Employed T cell receptor (TCR) transgenic mice with CD4(+) T cells specific for beta gal.
• Assessed immune responses through systemic immunization, adoptive T cell transfer, retinal enucleation, and delayed-type hypersensitivity assays.

Main Results:

• Retinal beta gal expression induced an immunoregulatory response that suppressed immune reactions to beta gal after systemic immunization.
• Regulatory T cells (CD3(+)4(+)25(+)) from beta gal-expressing mice transferred tolerance to naive recipients.
• Loss of the retina abolished the development of this regulatory response.
• Adoptive transfer of specific T cells into beta gal-expressing mice demonstrated regulatory activity, limiting T cell proliferation and inhibiting delayed-type hypersensitivity.

Conclusions:

• Peripheral expression of even minute amounts of tissue-specific antigens, such as retinal beta gal, can establish immune tolerance.
• This tolerance mechanism involves the generation and function of regulatory T cells.