New mechanisms and pathways for monocyte recruitment.
New mechanisms and pathways for monocyte recruitment.
复制标题
DOI：
10.1084/jem.194.9.f47
复制
发表时间：
2001-11-05
影响因子：
15.3
通讯作者：
Muller, W A
中科院分区：
文献类型：
--
作者：
Muller, W A
最近的大量研究已经确定了趋化剂和细胞激活剂负责中性粒细胞向炎症组织的运输，以及在稳定状态下淋巴细胞归巢到次级淋巴器官和慢性炎症的病灶(1-5)。关于调节单核细胞转运的分子，特别是健康时单核细胞通过组织的结构性转运和疾病中单核细胞向淋巴结的招募，人们所知的要少得多。本期《实验医学杂志》(6，7)上的两篇文章和最近一期(8)上的一篇文章揭示了这个问题，也引发了一些未来研究的问题。在老鼠的稳定状态下，每天大约有一半的循环单核细胞离开血流(9，10)。无效的单核细胞在脾内被破坏，但相当一部分循环单核细胞进入人体组织，分化为组织巨噬细胞(9，10)或树突状细胞(DC；参考文献11和12)。单个组织巨噬细胞的寿命是有争议的，但纹身的持久性证明了一个稳定的或自我更新的巨噬细胞群体在个人的一生中保持在适当的位置。相反，组织中的未成熟DC能够通过传入淋巴管离开，进入引流的淋巴结，在那里成熟，向T细胞递送抗原，并在到达后几天内死亡。因此，很大一部分单核细胞可能作为免疫监测的副产品被清除。在对炎症挑战做出反应的小鼠中，每天离开循环的单核细胞数量至少增加了一倍(10)。人类循环中单核细胞的半衰期大约是老鼠的三倍(13)，但人类的单核细胞质量是小鼠的1000倍，这意味着每天有3.4亿单核细胞离开血液循环。
A great deal of recent research has identified chemoattractants and cellular activators responsible for neutrophil trafficking into inflamed tissues, as well as for lymphocyte homing to secondary lymphoid organs in the steady state and into foci of chronic inflammation (1–5). Considerably less is known about the molecules regulating the trafficking of monocytes, particularly the constitutive trafficking of monocytes through tissues in health and the recruitment of monocytes to lymph nodes in disease. Two articles in this issue of The Journal of Experimental Medicine (6, 7) and one in a recent issue (8) shed some light on this subject and also prompt some questions for future investigation. Under steady-state conditions in mice about half of the circulating monocytes leave the bloodstream each day (9, 10). Effete monocytes are destroyed in the spleen, but a considerable fraction of circulating monocytes enter the tissues of the body, differentiating into tissue macrophages (9, 10) or dendritic cells (DCs; references 11 and 12). The lifespan of individual tissue macrophages is controversial, but the permanence of tattoos attests to the ability of a stable or self-renewing population of macrophages to be maintained in place for the lifetime of the individual. In contrast, immature DCs within the tissues are able to leave via afferent lymphatic vessels for the draining lymph nodes, where they mature, present antigen to T cells, and die within a few days of arrival. Thus, a large fraction of monocytes can potentially be cleared as a byproduct of immune surveillance.In mice responding to an inflammatory challenge, the number of monocytes leaving the circulation per day is at least double (10). The half-life of circulating monocytes in humans is about three times longer than in mice (13), but the thousandfold greater monocyte mass in humans means that 340 million monocytes leave the circulation each day.