Manetti R, Gerosa F, Giudizi M G, Biagiotti R, Parronchi P, Piccinni M P, Sampognaro S, Maggi E, Romagnani S, Trinchieri G
Division of Clinical Immunology and Allergy, University of Florence, Italy.
J Exp Med. 1994 Apr 1;179(4):1273-83. doi: 10.1084/jem.179.4.1273.
Interleukin 12 (IL-12) facilitates the generation of a T helper type 1 (Th1) response, with high interferon gamma (IFN-gamma) production, while inhibiting the generation of IL-4-producing Th2 cells in polyclonal cultures of both human and murine T cells and in vivo in the mouse. In this study, we analyzed the effect of IL-12, present during cloning of human T cells, on the cytokine profile of the clones. The culture system used allows growth of clones from virtually every T cell, and thus excludes the possibility that selection of precommitted Th cell precursors plays a role in determining characteristics of the clones. IL-12 present during the cloning procedures endowed both CD4+ and CD8+ clones with the ability to produce IFN-gamma at levels severalfold higher than those observed in clones generated in the absence of IL-12. This priming was stable because the high levels of IFN-gamma production were maintained when the clones were cultured in the absence of IL-12 for 11 d. The CD4+ and some of the CD8+ clones produced variable amounts of IL-4. Unlike IFN-gamma, IL-4 production was not significantly different in clones generated in the presence or absence of IL-12. These data suggest that IL-12 primes the clone progenitors, inducing their differentiation to high IFN-gamma-producing clones. The suppression of IL-4-producing cells observed in polyclonally generated T cells in vivo and in vitro in the presence of IL-12 is not observed in this clonal model, suggesting that the suppression depends more on positive selection of non-IL-4-producing cells than on differentiation of individual clones. However, antigen-specific established Th2 clones that were unable to produce IFN-gamma with any other inducer did produce IFN-gamma at low but significant levels when stimulated with IL-12 in combination with specific antigen or insoluble anti-CD3 antibodies. This induction of IFN-gamma gene expression was transient, because culture of the established clones with IL-12 for up to 1 wk did not convert them into IFN-gamma producers when stimulated in the absence of IL-12. These results suggest that Th clones respond to IL-12 treatment either with a stable priming for IFN-gamma production or with only a transient low level expression of the IFN-gamma gene, depending on their stage of differentiation.
白细胞介素12（IL - 12）促进1型辅助性T细胞（Th1）反应的产生，伴有高干扰素γ（IFN - γ）分泌，同时在人和鼠T细胞的多克隆培养物以及小鼠体内抑制分泌IL - 4的Th2细胞的产生。在本研究中，我们分析了克隆人T细胞过程中存在的IL - 12对克隆细胞因子谱的影响。所使用的培养系统允许几乎每个T细胞克隆生长，因此排除了预先确定的Th细胞前体的选择在决定克隆特征中起作用的可能性。克隆过程中存在的IL - 12使CD4⁺和CD8⁺克隆都具有产生IFN - γ的能力，其水平比在无IL - 12情况下产生的克隆中观察到的水平高几倍。这种启动是稳定的，因为当克隆在无IL - 12的情况下培养11天时，IFN - γ的高水平分泌得以维持。CD4⁺和一些CD8⁺克隆产生不同量的IL - 4。与IFN - γ不同，在有或无IL - 12情况下产生的克隆中，IL - 4的分泌没有显著差异。这些数据表明，IL - 12启动克隆祖细胞，诱导它们分化为高分泌IFN - γ的克隆。在本克隆模型中未观察到在体内和体外有IL - 12存在时多克隆产生的T细胞中所观察到的对分泌IL - 4细胞的抑制，这表明这种抑制更多地依赖于对非分泌IL - 4细胞的阳性选择，而不是单个克隆的分化。然而，不能被任何其他诱导剂诱导产生IFN - γ的抗原特异性已建立的Th2克隆，当与特异性抗原或不溶性抗CD3抗体联合用IL - 12刺激时，确实能以低但显著的水平产生IFN - γ。IFN - γ基因表达的这种诱导是短暂的，因为已建立的克隆在无IL - 12的情况下培养长达1周时，在用IL - 12刺激时不会转变为IFN - γ产生细胞。这些结果表明，Th克隆对IL - 12处理的反应要么是对IFN - γ产生的稳定启动，要么只是IFN - γ基因的短暂低水平表达，这取决于它们的分化阶段。
