A preparative ultracentrifuge for molecular studies on immune cell signaling

免疫系统不断地监控着哺乳动物的身体，以对抗各种来自身体内部或外部的危险信号。固有的危险信号包括需要清除的凋亡和死亡细胞、代谢物的异常积累（如痛风晶体）和肿瘤细胞的出现。外部危险信号包括身体损伤和微生物感染。免疫系统在两个层面上对这些侮辱做出反应。先天免疫系统的大多数细胞（中性粒细胞、巨噬细胞、肥大细胞、自然杀伤细胞等）提供第一道防线，没有特异性或记忆性，而某些其他细胞（树突状细胞、巨噬细胞）也有助于启动过继性免疫反应。后者由淋巴细胞介导，提供抗原特异性反应，留下记忆以有效应对未来的遭遇。虽然在了解先天免疫系统和过继免疫系统的功能方面取得了很大进展，但许多方面仍然不太清楚。

The immune system constantly monitors the mammalian body against all sorts of danger signals, arising from within the body or from outside. The intrinsic danger signals include apoptotic and dead cells that need to be cleared, abnormal accumulation of metabolites (e.g. gout crystals), and emergence of neoplastic cells. The outside danger signals include physical injury and microbial infections. The immune system responds to these insults at two levels. Most cells of the innate immune system (neutrophils, macrophages, mast cells, natural killer cells, etc) provide the first line of defense with no specificity or memory, while certain others (dendritic cells, macrophages) additionally help to initiate the adoptive immune response. The latter mediated by lymphocytes, provide antigen-specific responses that leave behind a memory to efficiently deal with future encounters. While great advances have been made in understanding the functions of the innate and adoptive immune systems, many aspects remain less clearly understood.