Maruo S, Toyo-oka K, Oh-hora M, Tai X G, Iwata H, Takenaka H, Yamada S, Ono S, Hamaoka T, Kobayashi M, Wysocka M, Trinchieri G, Fujiwara H
Biomedical Research Center, Osaka University Medical School, Japan.
J Immunol. 1996 Mar 1;156(5):1748-55.
We investigated the role of IL-12 in proliferation of various Th cell clones (class II-alloreactive (4-86 and 4-55) and keyhole limpet hemocyanin + self I-Ek-reactive (9-16)) following stimulation with Ag on APCs. These clones proliferated in response to stimulation with rIL-2, rIL-12, or Ag/APC. The proliferation induced by Ag/APC stimulation was not affected by anti-IL-2 Ab but was markedly inhibited by anti-IL-12 Abs. Consistent with this finding was the absence of detectable IL-2 activity in culture supernatants 12 to 48 h after Ag/APC stimulation, and the detection of significant levels of IL-12 in an Ab-capture bioassay. IL-12 was produced within 12 h after Ag/APC stimulation, reaching a peak after 18 to 24 h. The production of IL-12 in cultures of Th clones and APC contrasted with the production of IL-2 but not IL-12 upon allostimulation of primary T cells and the inhibition of their proliferation exclusively by anti-IL-2 Abs. Analysis of the expression of IL-12-binding sites on Th cells revealed low levels of IL-12 receptors in resting Th clones but high IL-12R levels 2 to 3 days after Ag/APC stimulation, declining gradually thereafter. The changes in IL-12R expression levels correlated closely with the IL-12 responsiveness of Th populations at various times after Ag/APC stimulation; Th populations obtained 3 and 10 days after Ag/APC stimulation exhibited very high and weak or marginal responsiveness to rIL-12, respectively, whereas the responses to rIL-2 were comparable in both Th populations. These results indicate that the Ag/APC-stimulated proliferation of terminally differentiated Th clones, in contrast to naive T cells, depends on the production of IL-12 by APC and on the simultaneous up-regulation of IL-12R on Th cells rather than on an IL-2 autocrine mechanism.
我们研究了白细胞介素-12（IL-12）在抗原呈递细胞（APC）上用抗原刺激后，对各种Th细胞克隆（II类同种异体反应性（4-86和4-55）以及钥孔戚血蓝蛋白+自身I-Ek反应性（9-16））增殖的作用。这些克隆对重组白细胞介素-2（rIL-2）、重组白细胞介素-12（rIL-12）或抗原/APC刺激有增殖反应。抗原/APC刺激诱导的增殖不受抗IL-2抗体的影响，但被抗IL-12抗体显著抑制。与此发现一致的是，在抗原/APC刺激后12至48小时的培养上清液中未检测到IL-2活性，而在抗体捕获生物测定中检测到显著水平的IL-12。IL-12在抗原/APC刺激后12小时内产生，在18至24小时后达到峰值。Th克隆和APC培养物中IL-12的产生与原代T细胞同种异体刺激时IL-2而非IL-12的产生形成对比，且其增殖仅被抗IL-2抗体抑制。对Th细胞上IL-12结合位点表达的分析显示，静息Th克隆中IL-12受体水平较低，但在抗原/APC刺激后2至3天IL-12R水平较高，此后逐渐下降。IL-12R表达水平的变化与抗原/APC刺激后不同时间Th群体对IL-12的反应性密切相关；抗原/APC刺激后3天和10天获得的Th群体分别对rIL-12表现出非常高和微弱或边缘性的反应性，而两者对rIL-2的反应相当。这些结果表明，与未成熟T细胞相比，终末分化的Th克隆在抗原/APC刺激下的增殖依赖于APC产生的IL-12以及Th细胞上IL-12R的同时上调，而非依赖于IL-2自分泌机制。
