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Alfred D Eaton

Publications and source records attributed to Alfred D Eaton.

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Internet↗

Regulatory T cells inhibit protein kinase C theta recruitment to the immune synapse of naive T cells with the same antigen specificity.

The precise mechanisms by which regulatory T cells operate, particularly their effect on signaling pathways leading to T cell activation, are poorly understood. In this study we have used regulatory T (Treg) cells of known Ag specificity, generated in vivo, to address their effects on early activation events occurring in naive T cells of the same Ag specificity. We found that the Treg cells need to be present at the moment of priming to suppress activation and proliferation of the naive T cell. Furthermore, the Treg cells significantly inhibit the recruitment of protein kinase Ctheta (PKCtheta) to the immune synapse of the naive T cell as long as both T cells are of the same Ag specificity and are contacting the same APC. Finally, naturally occurring CD4(+)25(+) T cells seem to have the same effect on PKCtheta recruitment in CD25(-) T cells of the same Ag specificity. These results suggest that although additional mechanisms of regulation are likely to exist, inhibition of PKCtheta recruitment in the effector T cell may be a common regulatory pathway leading to the absence of NF-kappaB activation and contributing to the block of IL-2 secretion characteristic of immune suppression.

Animals↗

Administration of exogenous interleukin-18 and interleukin-12 prevents the induction of oral tolerance.

Interleukin-18 (IL-18), a pro-inflammatory member of the IL-1 family, has been associated with autoimmunity and allergic disease. This type of pathology is thought to be the result of a defect in immunological tolerance and is often observed in inflammatory disorders of the gut such as coeliac disease, Crohn's disease and ulcerative colitis. IL-18 has been implicated in a number of mucosal immune disorders, where it synergizes with IL-12 to induce the production of interferon-gamma (IFN-gamma). We have therefore investigated the effects of IL-18 and IL-12 administration on the induction of oral tolerance to ovalbumin. The suppression of specific Ig G2a production, delayed-type hypersensitivity responses and IFN-gamma production by antigen-specific T cells were all abrogated by the presence of exogenous IL-12 and IL-18, suggesting that oral tolerance was broken. The expression of the co-stimulatory molecule CD80 on dendritic cells was also shown to be increased by this combination of cytokines. As dendritic cells are thought to be of major importance in the induction of tolerance, this suggests a mechanism by which tolerance to mucosal antigens may be broken in vivo.

Administration, Oral↗