晚发型阿尔茨海默病β淀粉样蛋白及过磷酸化tau蛋白免疫组织化学分析

Immunohistochemical analysis of β-amyloid and AT8 in late-onset Alzheimer＇ s disease

目的探讨中国人晚发型阿尔茨海默病（LOAD）的神经病理学特征，确保其正确诊断。方法选择经病理证实的8例LOAD患者和5名无神经系统相关疾病的老年对照者的颞叶脑皮质，为死亡后13～101h尸检取脑，双侧颞叶皮质取材。常规脱水、透明、石蜡包埋。连续切片，厚度6μm，β淀粉样蛋白（Aβ）及过磷酸化tau蛋白（AT8）免疫组织化学染色（S／P法），相邻切片作阴性对照。光镜下观察两组颞叶皮质阳性分布情况。结果LOAD组Aβ及AT8免疫组织化学染色均为阳性，AB阳性表达者分布于皮质各层，大小不一，形态各异，可见早期弥散斑、初级斑和终末斑等；AT8阳性表现为皮质神经元内不同程度神经原纤维缠结、神经毡细丝及老年斑。经半定量统计分析，Aβ免疫组织化学染色LOAD组全部阳性，其中中度阳性（＋＋）5例，强阳性（＋＋＋）3例；对照组阳性率为0。AT8免疫组织化学染色LOAD组中度阳性（＋＋）3例，强阳性（＋＋＋）5例，阳性率100％；对照组中度阳性（＋＋）1例（1／5），阴性（-）4例。LOAD组与对照组Aβ及AT8染色阳性率比较，差异有统计学意义（Х^2=13．000，P=0．001;Х^2=9．244，P=0．007）。结论Aβ免疫组织化学染色法能清晰显示各种类型老年斑；AT8免疫组织化学染色法可清晰显示各级神经原纤维缠结的不同变化。两种染色方法结合使用可提高LOAD患者的诊断率。

Objective To study the neuropathological characteristics of late-onset Alzheimer＇ s disease （LOAD） in Chinese people, to ensure correct diagnosis of LOAD. Methods Choosing cerebral cortex of temporal layer of 8 cases of LOAD and 5 cases of age-matched normal control group by autopsy. Histopathologic diagnosis was established in all these 13 cases. Cerebral cortex were taken from temporal layer in 13-101 hours after death and were fixed with 40 g/L paraformaldehyde, followed by paraffinembedding and serial sectioning with 6 μm thickness. Brain tissue was analyzed neuropatholically by using immunohistochemical staining for β-amyloid （Aβ） and AT8 on these cases. Positive distribution of temporal layer was observed under light microscope. Results The results of immunohistochemical stainings of Aβ and AT8 were positive in all of LOAD. Aβ immnnoreactant located in the cerebral cortex. The diffuse plaques, primitive plaques and burn-out plaques of senile plaques were displayed clearly by immunohistochemical stainings of Aβ. AT8 immunoreactants showed neurofibrillary tangles, neuropil thread and senile plaques in nerve cell of cerebral cortex in different degree respectively. The positive rate Aβ and AT8 were both 8/8 by semiquantitative analysis in AD group. As the normal aging control group, which was 0 and 1/5 respectively. There was significant difference of the positive rate Aβ and AT8 in two groups（Х^2 = 13. 000,P = 0. 001 ;Х^2 = 9.244, P = 0.007）. Conclusions Sensitive immunohistochemical technique was significant to display senile plaques and neurofibrillary tangles. The findings demonstrate that immunohistochemistry staining of Aβ and AT8 can display senile plaques and neurofibrillary tangles clearly. The connection of the 2 different methods might improve diagnose accordance rate of AD.