Mechanisms of oral tolerance: Antigen dose

Oral tolerance is mediated through different mechanisms, depending upon the antigen dose.
(A) Low doses of ingested antigen induce tolerance via activation of regulatory T cells that produce suppressive cytokines, such as IL-10 and TGF-beta.
(B) High doses of oral antigen lead to induction of tolerance via anergy (TCR cross-linking occurs without costimulation) or deletion (TCR is cross-linked in the presence of inhibitory molecules, CD95 and CD95L, leading to FAS-mediated apoptosis).