Dohlsten M, Björklund M, Sundstedt A, Hedlund G, Samson D, Kalland T
Wallenberg Laboratory, University of Lund, Sweden.
Immunology. 1993 Aug;79(4):520-7.
The response of mouse T cells to the superantigen staphylococcal enterotoxin A (SEA) requires 1000-fold higher concentrations compared to human T cells. In order to develop a sensitive model for SEA studies in mice, the immunopharmacology has been studied in T-cell receptor (TcR) V beta 3 transgenic (TGV beta 3) and non-transgenic (non-TG) C57Bl/6 mice. The frequency of SEA-responsive T cells in the TGV beta 3 mice exceeded 90%, whereas a 10-fold lower frequency was seen in normal C57Bl/6 mice. Nanograms of SEA injected intravenously into TGV beta 3 mice induced strong cytolytic T lymphocyte (CTL) activity against SEA-coated major histocompatibility complex (MHC) class II+ B-lymphoma cells, whereas administration of 1000-fold higher amounts of SEA to non-TG littermates or normal C57Bl/6 mice induced only a moderate response. Kinetic analysis demonstrated that the CTL activity was more rapidly detectable in TG mice, but substantial levels were seen 2 days after SEA injection in both TGV beta 3 and non-TG mice. The cytotoxic T-cell response induced by SEA in TGV beta 3 and non-TG mice was completely MHC class II dependent, as SEA-coated MHC class II-transfected syngeneic B16 melanoma cells but not untransfected B16 cells were sensitive to lysis. Large amounts of tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) accumulated in serum of TGV beta 3 mice after injection of 10 ng SEA, whereas only marginal amounts were recorded in non-TG even after injection of 100 micrograms SEA. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis demonstrated that SEA-induced TNF-alpha and IFN-gamma mRNA reached maximal levels 1 hr after SEA administration in TGV beta 3 mice, whereas peak serum levels of TNF-alpha and IFN-gamma proteins were recorded after 2 hr. Comparison of the mRNA levels of a panel of cytokines in the TGV beta 3 and non-TG mice revealed that almost similar amounts of interleukin-1 (IL-1) were induced in both strains, whereas IL-4 was only detected at significant levels in the TGV beta 3 mouse. The results suggest that TGV beta 3 mice are suitable for studying in vivo immune responses to superantigens at concentrations comparable to the potent effects elicited in humans. Moreover, this model is useful for detailed studies on the dynamic regulation of T-cell activation and anergy induced by superantigens.
与人类T细胞相比，小鼠T细胞对超抗原葡萄球菌肠毒素A（SEA）的反应需要高1000倍的浓度。为了开发一种用于小鼠SEA研究的敏感模型，对T细胞受体（TcR）Vβ3转基因（TGVβ3）和非转基因（非TG）C57Bl/6小鼠的免疫药理学进行了研究。TGVβ3小鼠中SEA反应性T细胞的频率超过90%，而正常C57Bl/6小鼠中的频率低10倍。静脉注射到TGVβ3小鼠体内的纳克级SEA诱导了针对SEA包被的主要组织相容性复合体（MHC）II类+B淋巴瘤细胞的强烈细胞毒性T淋巴细胞（CTL）活性，而给非TG同窝小鼠或正常C57Bl/6小鼠注射高1000倍剂量的SEA仅诱导了中等反应。动力学分析表明，TG小鼠中CTL活性更快速可检测到，但在SEA注射后2天，TGVβ3和非TG小鼠中均可见大量水平。SEA在TGVβ3和非TG小鼠中诱导的细胞毒性T细胞反应完全依赖于MHC II类，因为SEA包被的MHC II类转染的同基因B16黑色素瘤细胞对裂解敏感，而未转染的B16细胞则不敏感。注射10 ng SEA后，TGVβ3小鼠血清中积累了大量肿瘤坏死因子-α（TNF-α）和干扰素-γ（IFN-γ），而即使注射100μg SEA，非TG小鼠中也仅记录到少量。逆转录酶-聚合酶链反应（RT-PCR）分析表明，SEA诱导的TNF-α和IFN-γ mRNA在TGVβ3小鼠中SEA给药后1小时达到最高水平，而TNF-α和IFN-γ蛋白的血清峰值水平在2小时后记录。比较TGVβ3和非TG小鼠中一组细胞因子的mRNA水平发现，两种品系中诱导的白细胞介素-1（IL-1）量几乎相似，而IL-4仅在TGVβ3小鼠中以显著水平检测到。结果表明，TGVβ3小鼠适合于研究与人类中引发的强效效应相当浓度下对超抗原的体内免疫反应。此外，该模型对于超抗原诱导的T细胞活化和无反应性的动态调节的详细研究很有用。
