Fierz W, Endler B, Reske K, Wekerle H, Fontana A
J Immunol. 1985 Jun;134(6):3785-93.
Ia antigens seem to control immune responses on at least two levels. First, they influence the antigen recognition repertoire of the T cells. Second, their variable expression on certain antigen-presenting cells is a powerful regulatory mechanism for the local immune reaction. This is particularly important in the central nervous system (CNS) in which no Ia antigens are normally expressed. Recent experiments in this context have shown that astrocytes are able to express Ia antigens during interaction with T cells, and that they function as antigen-presenting cells. The Ia-inducing activity is produced by activated T cells, and can be replaced by immune interferon (IFN-gamma). In this study we report on the functional and kinetic relationship between Ia antigen expression on astrocytes and the immune-specific activation of T cells by astrocytes. Normal resting astrocytes were found to be negative for Ia antigens by immunofluorescence and by biochemical criteria. Moreover, they are only able to stimulate T cells after they have been induced to express Ia antigens by a signal from the T cells, which is probably mediated by IFN-gamma. In conclusion, the immune-specific interaction between astrocytes and T lymphocytes is a sensitively controlled system that might be pivotal to the development of immune responses in the brain. Malfunction of the system could be an important factor in the pathogenesis of aberrant immune reactions in the CNS, e.g., in multiple sclerosis.
Ia抗原似乎至少在两个层面上控制免疫反应。首先，它们影响T细胞的抗原识别谱。其次，它们在某些抗原呈递细胞上的可变表达是局部免疫反应的一种强大调节机制。这在中枢神经系统（CNS）中尤为重要，因为中枢神经系统通常不表达Ia抗原。在这方面的最新实验表明，星形胶质细胞在与T细胞相互作用期间能够表达Ia抗原，并且它们作为抗原呈递细胞发挥作用。Ia诱导活性由活化的T细胞产生，并且可以被免疫干扰素（IFN-γ）替代。在本研究中，我们报告了星形胶质细胞上Ia抗原表达与星形胶质细胞对T细胞的免疫特异性激活之间的功能和动力学关系。通过免疫荧光和生化标准发现，正常静止的星形胶质细胞Ia抗原呈阴性。此外，只有在它们被T细胞发出的信号诱导表达Ia抗原后，它们才能够刺激T细胞，这可能是由IFN-γ介导的。总之，星形胶质细胞与T淋巴细胞之间的免疫特异性相互作用是一个受到敏感控制的系统，可能对大脑中免疫反应的发展至关重要。该系统的功能障碍可能是中枢神经系统异常免疫反应发病机制中的一个重要因素，例如在多发性硬化症中。
