Tolerance and immunity in the intestinal immune system.

Area of Science:

• Immunology
• Gastroenterology
• Microbiology

Background:

• The intestinal immune system balances pathogen defense with tolerance to food antigens.
• Oral antigen administration typically induces systemic nonresponsiveness in the absence of inflammation.
• This tolerance is linked to T-cell anergy and the role of gut-associated lymphoid tissue.

Purpose of the Study:

• To review recent findings on the regulation of intestinal immune tolerance and immunity.
• To elucidate the mechanisms underlying orally induced antigen-specific nonresponsiveness.
• To understand the role of regulatory T cells in maintaining intestinal homeostasis.

Main Methods:

• Review of recent scientific literature on oral tolerance and intestinal immunity.
• Analysis of studies investigating T-cell activation, anergy, and regulatory T cell function.
• Examination of the impact of adjuvants on oral antigen presentation and immune response.

Main Results:

• Peripheral nonresponsiveness to oral antigens involves transient T-cell activation and functional T-cell anergy.
• Gut-associated lymphoid tissue supports regulatory T cell development, crucial for homeostasis.
• Gut-derived regulatory T cells can mediate tolerance in peripheral sites.
• Adjuvants can convert normally tolerogenic oral antigens into immunogenic forms.

Conclusions:

• The intestinal immune system employs sophisticated mechanisms to maintain tolerance to dietary antigens.
• Regulatory T cells originating in the gut play a vital role in systemic immune tolerance.
• Understanding these mechanisms is key to modulating immune responses in the gut and systemically.