The role of MHC class II in the control of T-cell responses to self and foreign antigens is still unclear. No unifying principle yet explains how class II molecules repress immunity to self or allogeneic antigens. Our recent data in a model of tolerance to allogeneic grafts, probably induced by allele-specific class II peptides, suggest that it is by presenting themselves [class II peptide(s) docked on self class II, in a complex we have named T-Lo] that class II controls T-cell activity. The engagement of the regulatory T (T-reg)-cell T-cell receptor (TCR) with self T-Lo would explain the beneficial effect of donor-recipient class II matching in clinical transplantation, the correlation between T-cell suppression and class II, and the altered T-reg-cell functions observed in class II-dependent autoimmune pathologies.

中文翻译：

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MHC II类自我表现调节T细胞功能。

MHC II类在控制T细胞对自身和外来抗原的反应中的作用仍不清楚。尚无统一原理可解释II类分子如何抑制对自身或同种异体抗原的免疫力。我们最近在对同种异体移植物的耐受性模型中的数据（可能由等位基因特异性的II类肽诱导）表明，这是通过将自身[对接于自身II类的II类肽呈现出来的，我们将其命名为T- II类控制T细胞活性。调节性T（T-reg）细胞T细胞受体（TCR）与自身T-Lo的结合将解释供体-受体II类匹配在临床移植中的有益作用，以及T细胞抑制与类II，以及在II类依赖性自身免疫病理中观察到的T-reg细胞功能改变。