A Study of Initial Stages of Immune Responses

我们用停流荧光法研究了辅助性T细胞内细胞内游离钙离子的增加。结果表明，T细胞受体可以非常迅速地识别异源抗原物和主要组织相容性抗原，并向辅助性T细胞传递刺激信号。当T细胞与外来抗原或MHC抗原混合时，没有观察到任何初始信号。这些结果还表明，在抗原呈递过程中，外来抗原和FIHC抗原的稳定复合体并不总是必需的，特别是对于小抗原。然后，我们研究了辅助T细胞与抑制T细胞相互作用后发生的初始事件。我们发现，如果两种细胞具有相同的抗原和FIHC限制性特异性，MHC限制性辅助性T细胞胞浆内游离钙离子的增加可以被激活的抑制性T细胞完全抑制。这种抑制作用是单向的，因为抑制者T细胞可以抑制辅助T细胞的激活，但反之亦然。这些结果首次证实了抑制T细胞和辅助T细胞之间的单向抑制细胞相互作用所引起的胞浆初始事件。最后，我们用视频增强显微镜检测了单个T细胞中的钙信号。当辅助性T细胞被抗原提呈细胞刺激时，钙离子会在一段滞后时间后从外部介质迅速转运到辅助性T细胞。我们发现单个Heiger T细胞中的钙反应是抗原和MHC特异性的。我们还发现，即使细胞被克隆，辅助T细胞在钙信号中的分布也是多种多样的。

We have studied by stopped-flow fluorometry the increase in free cytoplasmic calcium ion, an intracellular messenger for cell activation, in helper T cells.The results showed that T-cell receptors recognize both a foreign antien and a MHC antigen very rapidly (within 1 s), delivering stimulatory signals to the helper T cells. None of the initial signals were observed when T cells were mixed with either a foreign antigen or a MHC antigen. The results also suggest that a stable complex of a foreign antigen with a FIHC antigen is not always necessary in antigen presentation, especially for a small antigen.Then, we have studied the initial events occurring in the helper T cells following interaction with the suppressor T cells. We found that the early increase of increase of the cytoplasmic free calcium ion in the MHC-restricted helper T cells was completely inhibited by the activated suppressor T cells, provided both cell types have the same antigen- and FIHC-restriction specificities. This inhibitory effect is unidirectional in that the suppressor T cells can inhibit the activation of the helper T cells, but not vice versa. The results are the first to demonstrate the initial cytoplasmic event induced by the unidirectional suppressive cell interaction between the suppressor T cells and the helper T cells.Last, we detected the calcium signals in a single T cell by a video intensification microscopy. When helper T cells were stimulated with antigen-presenting cells, calcium ion was transported.rapidly after a lag time from the external medium into the helper T cells. We found that the calcium resdonses in single heiger T-cells were antigen- and MHC-specific. We found also that helper T-cells had a wide variety of the distribution of the la, times in the calcium signals, even if the cells were cloned.