Levin J
Department of Laboratory Medicine, University of California School of Medicine, San Francisco 94143.
Prog Clin Biol Res. 1988;272:3-15.
The roles of the amebocyte in providing hemostasis and controlling infection, and its reaction to endotoxin, suggest that the response of platelets and the blood coagulation system in various mammals to gram-negative infection or endotoxin is an evolutionary remnant of this ancient mechanism. In humans, this mechanism occasionally subverts its presumed protective function by overresponding in a manner that results in pathophysiologic thrombosis or hemorrhage. (In this regard, it is interesting that human platelets are much more resistant to the effects of bacterial endotoxins than are other species.) Similarly, the rudimentary ability of mammalian platelets to phagocytose particles and kill bacteria may be another remnant of functions that are more important in amebocytes (or the thrombocytes of other invertebrates). Thus, these two cells, one from an ancient invertebrate and the other from mammals, have remarkably similar characteristics, although the relative importance of their various functions has changed as evolution has taken place. Nevertheless, after at least 400,000,000 years of evolution, coagulation and anti-bacterial mechanisms remain at least partially linked.
变形细胞在止血和控制感染方面的作用，以及它对内毒素的反应，表明各种哺乳动物的血小板和血液凝固系统对革兰氏阴性感染或内毒素的反应是这种古老机制的进化残余。在人类中，这种机制偶尔会以导致病理生理血栓形成或出血的方式过度反应，从而颠覆其假定的保护功能。（在这方面，有趣的是，人类血小板比其他物种对细菌内毒素的影响更具抵抗力。）同样，哺乳动物血小板吞噬颗粒和杀死细菌的基本能力可能是在变形细胞（或其他无脊椎动物的血小板）中更重要的功能的另一个残余。因此，这两种细胞，一种来自古老的无脊椎动物，另一种来自哺乳动物，具有非常相似的特征，尽管随着进化的发生，它们各种功能的相对重要性已经改变。然而，经过至少4亿年的进化，凝血和抗菌机制至少部分仍然相关联。
