Augmented Induction of CD8+ Cytotoxic T cell Response and Antitumor Resistance by Thl-inducing peptide

效应CD 8 ^+ T细胞识别肿瘤细胞中表达的MHC I类结合改变的自身肽。虽然已经有文献证明CD 4 ^+ Th 1细胞在调节CD 8 ^+ T细胞中的作用，但它们的靶表位和在抗肿瘤反应中的功能影响仍不清楚。我们检测了是否存在分枝杆菌（M.）结核病引发的Th 1免疫有助于产生CD 8 ^+ T细胞，并对不相关的肿瘤特异性抗原产生保护性抗肿瘤免疫应答。肽-25是M.在C57 BL/6小鼠中，结核杆菌优先诱导CD 4 ^+ Thl细胞，并显示出对共免疫无关抗原肽的Thl产生的增强作用。用肽-25和OVA或肽-25和B16黑色素瘤肽（TRP-2）共免疫小鼠，分别导致对OVA和TRP-2肽特异的CD 8 ^+ T细胞显著增加。这种增强的反应依赖于肽-25特异性CD 4 ^+ I ...更多信息 产生FN-y的Th 1细胞。在肿瘤保护试验中，用肽-25和OVA免疫导致特异于OVA的CD 8 ^+细胞毒性细胞生成的增强和表达OVA肽的EL-4胸腺瘤的生长抑制，导致肿瘤排斥，这是单独用OVA免疫不能实现的。肽-25反应性Thl细胞在肽-25存在的情况下反活化树突状细胞（DC），导致它们活化OVA肽并将其呈递给CD 8 ^+细胞毒性T细胞。该结果表明，肽-25不仅自身诱导Thl应答，而且通过与CD 4 ^+ T细胞的相互作用诱导Thl诱导的DC活化。因此，我们产生了表达肽-25反应性克隆T细胞的TCR α链和β链的TCR转基因小鼠（P25 TCR-Tg），并分析了来自P25 TCR-Tg的CD 4 ^+ T细胞的Thl发育，以阐明肽-25诱导Thl分化的细胞和分子机制。在中性条件下，在I-A^B脾抗原呈递细胞存在的情况下，来自P25 TCR-Tg的初始CD 4 ^+ T细胞在肽-25刺激后优先产生Thl细胞。甚至在抗IFN-γ和抗IL-12存在下也观察到肽-25诱导的Th 1分化。此外，在不存在IFN-γ或IL-12的情况下，负载肽-25-I-A β b的转染的中国仓鼠卵巢细胞（肽-25-I-A β b-CHO）诱导初始CD 4 β + T细胞从P25 TCR-Tg分化为Thl。在用肽-25-I-A β b-CHO刺激TCR后3小时，通过定量RT-PCR观察到短暂的T-bet上调和加塔-3表达的抑制，这两者都不依赖于IFN-γ和IL-12。这些结果表明，肽-25/I-A^B b和TCR之间的相互作用可能主要影响幼稚CD 4 ^+ T细胞向Th 1亚群分化的命运。综上所述，这些结果表明肽-25发挥有效的佐剂活性，并为针对肿瘤抗原的CTL诱导提供有效的帮助。少

The effector CD8^+ T cells recognize MHC class I binding altered self-peptides expressed in tumor cells. Although the requirement for CD4^+ Th1 cells in regulating CD8^+ T cells has been documented, their target epitopes and functional impact in antitumor responses remain unclear. We examined whether a potent immunogenic peptide of Mycobacterium (M.) tuberculosis eliciting Thl immunity contributes to the generation of CD8^+ T cells and to protective antitumor immune responses to unrelated tumor-specific antigens. Peptide-25, a major Th epitope of Ag85B from M. tuberculosis preferentially induced CD4^+ Thl cells in C57BL/6 mice and showed an augmenting effect on Thl generation for coimmunized unrelated antigenic peptides. Coimmunization of mice with Peptide-25 and OVA or Peptide-25 and B16 melanoma peptide (TRP-2) for MHC class I led to a profound increase in CD8^+ T cells specific for OVA and TRP-2 peptides, respectively. This heightened response depended on Peptide-25 specific CD4^+ I … More FN-y-producing Th1 cells. In tumor protection assays, immunization with Peptide-25 and OVA resulted in the enhancement of CD8^+ cytotoxic cell generation specific for OVA and the growth inhibition of EL-4 thymoma expressing OVA peptide leading to the tumor rejection, that were not achieved by immunization with OVA alone. Peptide-25 reactive Thl cells counteractivated dendritic cells (DCs) in the presence of Peptide-25 leading them to activate and present OVA peptide to CD8^+ cytotoxic T cells. This result indicates that Peptide-25 not only induces a Thl-response by itself but also induces Thl-inducing activation of DCs through interactions with CD4^+ T cells. Therefore, we generated TCR transgenic mice (P25 TCR-Tg) expressing TCR a-and β-chains of Peptide-25-reactive cloned T cells and analyzed Thl development of CD4^+ T cells from P25 TCR-Tg to elucidate cellular and molecular mechanisms of the induction of Thl differentiation by Peptide-25. Naive CD4^+ T cells from P25 TCR-Tg preferentially develop Thl cells upon Peptide-25 stimulation in the presence of I-A^b splenic antigen-presenting cells under neutral conditions. Peptide-25-induced Thl differentiation is observed even in the presence of anti-IFN-y and anti-IL-12. Furthermore, Peptide-25-loaded I-A^b-transfected Chinese hamster ovary cells (Peptide-25-I-A^b-CHO) induce Thl differentiation of naive CD4^+ T cells from P25 TCR-Tg in the A^bsence of IFN-y or IL-12. Three hours after the TCR stimulation with Peptide-25-I-A^b-CHO, transient T-bet up-regulation and suppression of GATA-3 expression were observed by quantitative RT-PCR, both of which were independent of IFN-y and IL-12. These results imply that interaction between Peptide-25/I-A^b and TCR may primarily influence determination of the fate of naive CD4^+ T cells in their differentiation towards the Th1 subset. Taken together, these results indicate that Peptide-25 exerts potent adjuvant activity and provides efficient help for CTL induction against tumor antigen. Less