朊粒致病似乎绝大多数都是神经系统相关疾病，而且似乎也以神经退行性疾病为主
退行性好理解，但是为啥只有神经系统发病呢？而且血脑屏障在干什么？
朊粒对应的正常蛋白只在神经系统表达？或者其他细胞出问题可以募集免疫系统及时干掉自己？那心肌细胞呢？而且为毛神经细胞会内吞朊粒啊，从突触进去么……
@Lucy赤い月

因为神经细胞的表达比其他细胞要多得多吧？干的越多错的越多

prion表达的多的细胞有四类，神经细胞、胶质细胞、血系细胞、生殖细胞。各系血细胞可能是因为“玩完”的快，生殖细胞可能的确有什么机制所以处理蛋白质的“能力强”，所以很多人在研究生殖细胞在这方面的作用。
研究显示神经、胶质细胞抵抗不良遗传因素、氧化环境等使蛋白质聚集的不利因素的能力相对其她种类的细胞都是更“强”的，但神经细胞，单个细胞活的长，在关键的核团又是“一个萝卜一个坑”缺一不可，可能是蛋白质折叠疾病大多表现为神经退行性疾病的原因。

具体来说，PrpSC是从脂阀进去的，可能因为其和脂阀区需要正常转运进细胞的相关蛋白发生共聚了。

具体心肌应该是因为表达少，心肌还没来得及明显受累，神经系统就“玩完”了。

Prion 如果够小 BBB就没用了。

Although the amount of PrPC in brain is very high in contrast to other tissues, it represents less than 0.1% of the total central nervous system proteins. For example, from 100 hamster brains only a few micrograms of purified PrPC were obtained in an optimal procedure.
Riesner, Detlev. "Biochemistry and structure of PrPC and PrPSc." British medical bulletin 66.1 (2003): 21-33.
Here, we found that radioactively labeled PrPc crossed the BBB in both the brain-to-blood and blood-to-brain directions. PrPc was enzymatically stable in blood and in brain, was cleared by liver and kidney, and was sequestered by spleen and the cervical lymph nodes. Circulating PrPc entered all regions of the CNS, but uptake by the lumbar and cervical spinal cord,hypothalamus, thalamus, and striatum was particularly high.
Banks, W. A., et al. "Transport of prion protein across the blood–brain barrier." Experimental neurology 218.1 (2009): 162-167.

长知识了