Mehrotra P T, Wu D, Crim J A, Mostowski H S, Siegel J P
Laboratory of Cellular Immunology, Food and Drug Administration, Bethesda, MD 20892.
J Immunol. 1993 Sep 1;151(5):2444-52.
We have studied the effects of human rIL-12 on the proliferation and generation of cytotoxic activity in human CTL precursors. Purified human blood CD8+ T lymphocytes were stimulated overnight with immobilized alpha-CD3 and cultured 3 to 4 additional days under various conditions. The addition of IL-12 resulted in a marked (10- to 20-fold), dose-dependent, augmentation of cytotoxicity per cell with a smaller (2-fold) increase in cell number. IL-12 augmentation of proliferation and cytotoxicity of CD8+ T cells was not inhibited by a mAb to the p55 subunit of the IL-2 receptor (alpha-Tac) at a concentration sufficient to block the activity of exogenously added IL-2, indicating that the activity of IL-12 did not require IL-2. Addition of IL-12 at the time of alpha-CD3 activation or 1 day later was highly effective at augmenting cytotoxicity, whereas delayed addition of IL-12 (day 2 or 3) resulted in a smaller increase in CTL activity with no increase in cell number. IL-12 at all doses tested synergized with low dose IL-2 in inducing the proliferation and differentiation of CD8+ T cells. The synergistic effect was not blocked by adding neutralizing serum to IFN-gamma. In contrast to this synergistic effect, IL-12 significantly inhibited the proliferation observed in the presence of higher concentrations of IL-2 (4,500 and 13,500 pg/ml). An inhibitory effect of IL-12 was also observed when IL-12 was added to CD8+ T lymphocytes 3 days subsequent to activation with alpha-CD3 and IL-2. This broad set of potent effects of IL-12 on CD8+ T cell responses suggests that IL-12 may play an important immunoregulatory role on CTL development in vivo and may be a useful tool for manipulating this process in vivo for investigational and immunotherapeutic purposes.
我们研究了人重组白细胞介素-12（rIL-12）对人细胞毒性T淋巴细胞（CTL）前体细胞增殖及细胞毒性活性产生的影响。纯化的人血CD8⁺ T淋巴细胞用固定化的α-CD3刺激过夜，并在各种条件下再培养3至4天。添加IL-12导致每个细胞的细胞毒性显著增强（10至20倍），呈剂量依赖性，细胞数量增加较小（2倍）。IL-12增强CD8⁺ T细胞的增殖和细胞毒性不受抗IL-2受体p55亚基单克隆抗体（α-Tac）的抑制，该抗体浓度足以阻断外源性添加IL-2的活性，这表明IL-12的活性不需要IL-2。在α-CD3激活时或1天后添加IL-12在增强细胞毒性方面非常有效，而延迟添加IL-12（第2天或第3天）导致CTL活性增加较小且细胞数量无增加。在诱导CD8⁺ T细胞增殖和分化方面，所有测试剂量的IL-12都与低剂量IL-2协同作用。添加针对干扰素-γ的中和血清并未阻断这种协同作用。与这种协同作用相反，IL-12显著抑制在较高浓度IL-2（4500和13500 pg/ml）存在下观察到的增殖。在用α-CD3和IL-2激活3天后向CD8⁺ T淋巴细胞中添加IL-12时也观察到了IL-12的抑制作用。IL-12对CD8⁺ T细胞反应的这一系列广泛而有效的作用表明，IL-12可能在体内CTL发育中发挥重要的免疫调节作用，并且可能是用于体内操纵这一过程以进行研究和免疫治疗目的的有用工具。
