Usui M, Aoki I, Sunshine G H, Dorf M E
J Immunol. 1984 Sep;133(3):1137-41.
Third-order (Ts3) suppressor cells are generated after conventional immunization. These cells, however, will not mediate suppressor cell function unless specifically triggered by an activating signal, termed TsF2. This report analyzes the mechanism of this TsF2-mediated triggering event. TsF2-mediated suppression is genetically restricted by genes in the I-J and Igh-V regions. The target of the I-J restrictions is a firmly adherent accessory cell, which appears to express I-J-related determinants. These accessory cells are sensitive to cyclophosphamide treatment and 500 R irradiation. In contrast, the target of the Igh-V restriction of TsF2 appears to be the Ts3 cell, which carries antigen-specific, idiotype-related receptors. The mechanism of suppressor cell activation appears to involve two stages. Presentation of I-J-restricted TsF2 by I-J-compatible presenting cells and a second step involving idiotype-anti-idiotype interactions between TsF2 and the Ts3 cell. I-J compatibility is not required with the accessory cell for Ts3 activation. Finally, we hypothesize that the anti-idiotypic determinants expressed on TsF2 can serve as an internal image of antigen, thereby permitting specific targeting of the factor.
三级（Ts3）抑制细胞在常规免疫后产生。然而，这些细胞除非被一种称为TsF2的激活信号特异性触发，否则不会介导抑制细胞功能。本报告分析了这种由TsF2介导的触发事件的机制。TsF2介导的抑制在遗传上受I-J和Igh-V区域基因的限制。I-J限制的靶标是一种牢固黏附的辅助细胞，其似乎表达与I-J相关的决定簇。这些辅助细胞对环磷酰胺处理和500伦琴辐射敏感。相反，TsF2的Igh-V限制的靶标似乎是Ts3细胞，其携带抗原特异性、独特型相关受体。抑制细胞激活的机制似乎涉及两个阶段。由I-J兼容的呈递细胞呈递I-J限制的TsF2以及第二步，涉及TsF2与Ts3细胞之间的独特型-抗独特型相互作用。对于Ts3激活，辅助细胞不需要I-J兼容性。最后，我们推测在TsF2上表达的抗独特型决定簇可作为抗原的内影像，从而使该因子能够进行特异性靶向。
