REGULATION OF HUMAN T CELL FUNCTIONS BY INTERLEUKIN 12 (IL-12)

众所周知，IL-12上调干扰素-γ的合成 (干扰素-g)在活化的T细胞中；然而，IL-12对表达的影响 其他细胞因子的定义不是很好。在这个项目中，我们是 检测IL-12对多种细胞因子产生的影响， 包括干扰素-g、白介素2、白介素10和肿瘤坏死因子-a，通过 纯化的正常人CD3T细胞。尽管静息T细胞 大部分IL-12无反应、抗CD3激活的T细胞母细胞高度 IL-12的反应性表现为IL-12诱导 STAT4介导的干扰素应答区(GRR)DNA结合 活动。我们发现，纯化的人T淋巴母细胞的激活 固定化抗CD3单抗诱导肿瘤坏死因子-αmRNA快速表达 IL-2、干扰素-g和IL-10的mRNA水平逐渐升高。IL-12 显著上调干扰素-g和白介素10的表达，下调 IL-2的产生。IL-12对IL-2产生的抑制作用 直接与IL-10的产生增加有关。此外，中和 IL-10活性与抗IL-10抗体联合应用可使IL-2产生正常化 在IL-12处理的T细胞中显示出抑制作用 IL-12是由IL-10介导的。因此，IL-12同时上调 产生干扰素-γ和白介素10，并通过直接依赖白介素10的途径， 反馈抑制IL-2的产生。IL-12差异显著的事实是 调节T细胞中干扰素-g和IL-2的合成表明IL-12 不会在全球范围内增强所有Th1型淋巴因子的表达。 此外，IL-12上调IL-10产生的能力 提供一种机制来限制依赖IL-2的克隆性扩张 激活T细胞，并定义了一种新的细胞因子调节途径， 是IL-12诱导的。在未来的研究中，我们计划进一步定义 IL-12对活化T细胞产生细胞因子的影响 IL-12与其他巨噬细胞来源的作用的比较 免疫调节细胞因子，特别是IL-1β和肿瘤坏死因子-α。我们 还将进一步探讨IL-10升高的功能后果 IL-12处理的T细胞的产生。这些研究的结果将 拓宽我们目前对IL-12在免疫中作用的理解 效应细胞。此信息可能有助于解释任何 目前正在进行临床试验中IL-12诱导的治疗活性。 它还可以提供对某些特定的生理基础的洞察 与大剂量IL-12治疗相关的毒性反应。

It is well known that IL-12 up-regulates synthesis of interferon-gamma (IFN-g) in activated T cells; however, the effects of IL-12 on expression of other cytokines are not well defined. In this project, we are examining the effects of IL-12 on production of multiple cytokines, including IFN-g, IL-2, IL-10 and tumor necrosis factor-a (TNF-a), by purified, normal human CD3+ T cells. Although resting T cells are largely IL-12-nonresponsive, anti-CD3-activated T cell blasts are highly IL-12-responsive as demonstrated by the ability of IL-12 to induce Stat4-mediated gamma-interferon response region (GRR) DNA-binding activity. We have found that activation of purified human T lymphoblasts on immobilized anti-CD3 mAb induces rapid expression of TNF-a mRNA, and a more gradual increase in mRNA levels for IL-2, IFN-g and IL-10. IL-12 markedly up-regulates expression of IFN-g and IL-10, and down-regulates production of IL-2. Inhibition of IL-2 production by IL-12 correlates directly with increased production of IL-10. Moreover, neutralization of IL-10 activity with anti-IL-10 antibodies normalizes IL-2 production in IL-12-treated T cells demonstrating that the inhibitory effects of IL-12 are IL-10-mediated. Thus, IL-12 simultaneously up-regulates production of IFN-g and IL-10, and, by a direct IL-10-dependent pathway, feedback inhibits production of IL-2. The fact that IL-12 differentially regulates synthesis of IFN-g and IL-2 in T cells demonstrates that IL-12 does not globally enhance expression of all Th1-type lymphokines. Furthermore, the ability of IL-12 to up-regulate production of IL-10 provides a mechanism for limiting IL-2-dependent clonal expansion of activated T cells, and defines a novel cytokine regulatory pathway that is inducible by IL-12. In future studies, we plan to further define the effects of IL-12 on cytokine production by activated T cells, and to compare the effects of IL-12 with that of other macrophage-derived immunoregulatory cytokines, particularly IL-1 beta and TNF-alpha. We will also further explore the functional consequences of increased IL-10 production in IL-12-treated T cells. The results of these studies will broaden our present understanding of the actions of IL-12 on immune effector cells. This information may be useful in interpreting any therapeutic activity induced by IL-12 in clinical trials now underway. It may also provide insight to the physiological basis for certain toxicities associated with high dose IL-12 therapy.