Brighton Sussex Medical School, Department of Nuclear Medicine, Royal Sussex County Hospital, Brighton, UK.
Med Hypotheses. 2012 Jan;78(1):26-8. doi: 10.1016/j.mehy.2011.09.033. Epub 2011 Nov 15.
It is not known why metastases from epithelial cancers are rare in the spleen, yet common in the other major organs of the reticuloendothelial system in which, like the spleen, leucocytes display a prolonged physiological intravascular transit time. Another unresolved issue that at first seems unrelated to splenic metastases is the inconsistency between the concept of physiological granulocyte disposal through granulocyte ageing and the observation that granulocytes leave the blood in an exponential fashion (half-time 7 h), which implies random disposal. Intravascular granulocytes pass through the spleen with an exponential distribution of transit times (mean 10 min). The spleen is highly active in physiological granulocyte destruction so it is suggested that the variation in times of exposure to the splenic microenvironment converts the age-dependent granulocyte destruction observed ex vivo into the random process observed in vivo, probably through exposure to apoptosis-inducing signals. This leads to the second hypothesis, which is that cancer cells fail to survive in the spleen as a result of these pro-apoptotic signals.
目前尚不清楚为什么上皮癌的转移在脾脏中很少见，而在网状内皮系统的其他主要器官中很常见，在这些器官中，白细胞像脾脏一样表现出延长的生理血管内转运时间。另一个尚未解决的问题起初似乎与脾脏转移无关，即通过粒细胞老化实现生理粒细胞处置的概念与粒细胞以指数方式离开血液（半衰期 7 小时）的观察结果之间的不一致性，这意味着随机处置。血管内粒细胞以指数分布的转运时间（平均 10 分钟）通过脾脏。脾脏在生理粒细胞破坏中非常活跃，因此有人提出，暴露于脾微环境的时间变化将体外观察到的与年龄相关的粒细胞破坏转化为体内观察到的随机过程，可能是通过暴露于诱导凋亡的信号。这就引出了第二个假设，即癌细胞由于这些促凋亡信号而无法在脾脏中存活。
