Role of tumour necrosis factor-alpha in dendritic cell-mediated primary mixed leucocyte reactions.
Role of tumour necrosis factor-alpha in dendritic cell-mediated primary mixed leucocyte reactions.
复制标题
肿瘤坏死因子-α 在树突状细胞介导的原发性混合白细胞反应中的作用。
作者：
J. McKenzie;V. Calder;G. Starling;D. Hart
肿瘤坏死因子 (TNF α) 是一种主要的炎症细胞因子，对特异性免疫反应（包括移植物抗宿主病）具有增强作用。本研究探讨了 TNF α 对树突状细胞 (DC) 介导的原代同种异体 T 淋巴细胞反应的贡献。纯化的血液 DC 显示产生最少量的 TNF α mRNA，但通过 ELISA 测量，没有显着的 TNF 生物活性或分泌的 TNF α。使用 CD120a (TNFRI, p55) 和 CD120b (TNFRII, p75) 的寡核苷酸引物通过 PCR 扩增 DC mRNA，并用特定的内部寡核苷酸探测，表明 DC 表达 CD120b，但表达很少（如果有）CD120a。使用 TNF 受体的单克隆抗体证实了这些结果。 TNF α 特异性多克隆抗血清可阻断血液 DC 刺激的同种异体混合白细胞反应 (MLR)。将 TNF α 添加到次优 MLR（有限的 DC 刺激剂）中，会增加反应性 T 淋巴细胞的增殖。证实 T 淋巴细胞在刺激后产生 TNF α 并表达 CD120b，我们试图澄清 TNF α 对同种异体 MLR 的贡献作用是由 TNF α 介导的信号刺激 DC 活性引起的，还是由 T 淋巴细胞自分泌刺激的结果。 DC与TNFα预孵育并没有增加DC的刺激能力，并且后期添加抗TNF血清（长达72小时）仍然对MLR具有显着的抑制作用。我们得出的结论是，TNFα可能不参与最初的DC-T淋巴细胞相互作用，但作为DC诱导的T淋巴细胞增殖的自分泌生长因子。
Tumour necrosis factor (TNF alpha) is a major inflammatory cytokine with potentiating effects on specific immune responses, including graft-versus-host disease. This study examined the contribution of TNF alpha to dendritic cell (DC)-mediated primary allogeneic T lymphocyte responses. Purified blood DC were shown to produce minimal amounts of TNF alpha mRNA but no significant TNF biological activity or secreted TNF alpha as measured by ELISA. Amplification of DC mRNA by PCR using oligonucleotide primers to CD120a (TNFRI, p55) and CD120b (TNFRII, p75) and probing with specific internal oligonucleotides, suggested that DC express the CD120b but little if any CD120a. These results were confirmed using monoclonal antibodies to the TNF receptors. Polyclonal antiserum specific for TNF alpha blocked the blood DC-stimulated allogeneic mixed leucocyte reaction (MLR). The addition of TNF alpha to suboptimal MLRs (limited DC stimulators), increased the proliferation of responding T lymphocytes. Having confirmed that T lymphocytes produce TNF alpha and express CD120b after stimulation, we sought to clarify whether the contributing effect of TNF alpha to the allogeneic MLR resulted from a TNF alpha-mediated signal stimulating DC activity, or as a result of autocrine stimulation of T lymphocytes. Pre-incubation of DC with TNF alpha did not increase DC stimulatory capacity and late addition of anti-TNF serum (up to 72 h) still had a significant inhibitory effect on the MLR. We conclude that TNF alpha is probably not involved in the initial DC-T lymphocyte interaction, but acts as an autocrine growth factor for DC induced T lymphocyte proliferation.