Promiscuous gene expression and central T-cell tolerance: more than meets the eye.

Tumor Immunology Program, Division of Cellular Immunology, German Cancer Research Center, INF 280, D-69120 Heidelberg, Germany.
Trends in Immunology (Impact Factor: 12.03). 08/2002; 23(7):364-71. DOI: 10.1016/S1471-4906(02)02248-2
Source: PubMed
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    ABSTRACT: Since the first studies in immunology, there has been a clear need to understand how, under normal conditions, the immune system tolerates its own antigens and attacks some foreign antigens that it perceives as potentially dangerous and how, in certain circumstances, the loss of tolerance triggers autoimmune diseases. It has been over half a century since Billingham, Brent and Medawar demonstrated, in an experimental model, the mechanisms involved in the development of immunological tolerance. Since then transplant immunologists have intensively investigated the mechanisms involved in maintaining tolerance, in the hope of avoiding the complications of non-specific immunosuppression, as well as the prevention of chronic rejection. An important characteristic was observed by Medawar, who argued that during transplantation an individual's immune system is tolerant to transplanted tissue, maintaining the response to other antigens. Recent studies have shown that loss of tolerance to transplantation is associated with a hyper-response to antigens of the transplanted tissue; a problem that has plagued clinical immunologists, who have focused their efforts on developing accurate measurement systems to enable them to measure how an individual could be tolerant to transplant. Attempts to induce tolerance in the individual are based on understanding the basic mechanisms of tolerance, in which there has been significant progress. This growth in knowledge has been in parallel with a better appreciation of the complexity of immune tolerance. In particular, progress has been made in understanding the essential role of tolerogenic dendritic cells (CDS) and the maintenance of tolerance by regulatory T cells.
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    ABSTRACT: For reasons not fully understood, patients with an organ-specific autoimmune disease have increased risks of developing autoimmune responses against other organs/tissues. We identified ICA69, a known β-cell autoantigen in Type 1 diabetes, as a potential common target in multi-organ autoimmunity. NOD mice immunized with ICA69 polypeptides exhibited exacerbated inflammation not only in the islets, but also in the salivary glands. To further investigate ICA69 autoimmunity, two genetically modified mouse lines were generated to modulate thymic ICA69 expression: the heterozygous ICA69(del/wt) line and the thymic medullary epithelial cell-specific deletion Aire-ΔICA69 line. Suboptimal central negative selection of ICA69-reactive T-cells was observed in both lines. Aire-ΔICA69 mice spontaneously developed coincident autoimmune responses to the pancreas, the salivary glands, the thyroid, and the stomach. Our findings establish a direct link between compromised thymic ICA69 expression and autoimmunity against multiple ICA69-expressing organs, and identify a potential novel mechanism for the development of multi-organ autoimmune diseases.
    Journal of Autoimmunity 08/2014; · 7.02 Impact Factor

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