Anderton Stephen M, Wraith David C
Institute of Cell, Animal and Population Biology, University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3JT, UK.
Nat Rev Immunol. 2002 Jul;2(7):487-98. doi: 10.1038/nri842.
The immune system must avoid aggressive T-cell responses against self-antigens. But, paradoxically, exposure to self-peptides seems to have an important role in positive selection in the thymus and the maintenance of a broad T-cell repertoire in the periphery. Recent experiments have highlighted situations that allow high-avidity self-reactive T cells to avoid negative selection in the thymus. Accumulating evidence indicates that other, non-deleting mechanisms control the avidity with which T cells recognize self-antigens--a phenomenon that is known as 'tuning'. This might maximize the peripheral T-cell repertoire by allowing the survival of T cells that can respond to self, but only at concentrations that are not normally reached in vivo.
免疫系统必须避免对自身抗原产生强烈的T细胞反应。但矛盾的是，接触自身肽似乎在胸腺中的阳性选择以及外周广泛T细胞库的维持中发挥着重要作用。最近的实验突出了一些情况，即高亲和力的自身反应性T细胞能够避免在胸腺中被阴性选择。越来越多的证据表明，其他非清除机制控制着T细胞识别自身抗原的亲和力——这一现象被称为“调节”。这可能通过允许能够对自身做出反应但仅在体内通常不会达到的浓度下做出反应的T细胞存活，从而使外周T细胞库最大化。
