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T cell immunity to oral allergens
1Department of Paediatric Gastroenterology St Bartholomews and the Royal London School of Medicine and Dentistry St Bartholomews Hospital London EC1A 7BE UK. t.t.macdonald@mds.qmw.ac.uk
Current Opinion in Immunology
|January 23, 1999
Summary
Oral tolerance, or orally-induced systemic tolerance, involves T cell anergy, apoptosis, and the induction of regulatory T cells (Th3 cells) secreting transforming growth factor beta. Food antigens impact systemic T cells, challenging prior notions about mucosal immunity.
Area of Science:
- Immunology
- Gastroenterology
Background:
- Oral tolerance is a complex immunological process where the immune system becomes unresponsive to antigens introduced orally.
- Recent research has elucidated key mechanisms, including T cell anergy, apoptosis, and the generation of regulatory T cells.
Purpose of the Study:
- To review and synthesize recent findings on the mechanisms of oral tolerance.
- To discuss the systemic effects of food antigens on T cell responses.
- To evaluate the clinical implications and outcomes of oral tolerance therapies.
Main Methods:
- Review of recent immunological studies on oral tolerance.
- Analysis of T cell responses to orally administered antigens.
- Examination of regulatory T cell induction and function (e.g., Th3 cells, TGF-beta).
Main Results:
- Oral administration of antigens can induce T cell anergy and apoptosis.
- A major pathway involves the induction of regulatory T cells (Th3 cells) that secrete transforming growth factor beta (TGF-β).
- Food antigens exert significant systemic effects on T cells, similar to intravenously administered soluble antigens, suggesting antigen type, not just tissue location, dictates response.
Conclusions:
- Oral tolerance mechanisms are multifaceted, involving both T cell deletion and regulation.
- The systemic impact of food antigens highlights the interconnectedness of mucosal and systemic immunity.
- Despite promising initial research, clinical applications of oral tolerance for autoimmune diseases have yielded disappointing results thus far.