Dixon Giles, Elks Philip M, Loynes Catherine A, Whyte Moira K B, Renshaw Stephen A
MRC Centre for Developmental and Biomedical Genetics, University of Sheffield School of Medicine, Sheffield S10 2RX, UK.
ISRN Hematol. 2012;2012:915868. doi: 10.5402/2012/915868. Epub 2012 Jul 16.
Neutrophil function is thought to be regulated, in large part, by limitation of lifespan by apoptosis. A number of studies suggest that circulating neutrophils have a half-life of approximately 6 hours, although contradictory evidence exists. Measuring tissue neutrophil lifespan, however, is more problematic. It is thought that tissue neutrophils survive longer, perhaps with a half-life in the order of 3-5 days, but this has never been directly measured. Zebrafish are an emerging model organism, with several advantages for the study of vertebrate immunity. In zebrafish, neutrophils constitutively assume tissue locations allowing their direct study in vivo. Using a transgenic approach, neutrophils were labelled with a photoconvertible pigment, Kaede. Photoconversion parameters were optimised and the stability of the Kaede confirmed. Individual neutrophils were photoconverted by scanning a confocal 405 nm laser specifically over each cell and their survival monitored for 48 hours, revealing an in vivo half-life for zebrafish tissue neutrophils of around 120 hours (117.7 hrs, 95% CI 95.67-157.8). Laser energy did not extend neutrophil lifespan, and we conclude that this represents a lower bound for the lifespan of a resting tissue neutrophil in the developing zebrafish larva. This is the first direct measurement of the lifespan of an in vivo tissue neutrophil.
中性粒细胞的功能在很大程度上被认为是由细胞凋亡导致的寿命限制所调节的。许多研究表明，循环中的中性粒细胞半衰期约为6小时，尽管也存在相互矛盾的证据。然而，测量组织中中性粒细胞的寿命则更具问题。据认为，组织中的中性粒细胞存活时间更长，其半衰期可能在3至5天左右，但这从未被直接测量过。斑马鱼是一种新兴的模式生物，在脊椎动物免疫研究方面具有多个优势。在斑马鱼中，中性粒细胞会持续占据组织位置，从而便于在体内对其进行直接研究。采用转基因方法，用一种光转化色素Kaede标记中性粒细胞。优化了光转化参数并确认了Kaede的稳定性。通过在共聚焦405纳米激光下专门扫描每个细胞，对单个中性粒细胞进行光转化，并对其存活情况监测48小时，结果显示斑马鱼组织中性粒细胞在体内的半衰期约为120小时（117.7小时，95%置信区间为95.67 - 157.8）。激光能量并未延长中性粒细胞的寿命，我们得出结论，这代表了发育中的斑马鱼幼虫体内静息组织中性粒细胞寿命的下限。这是首次对体内组织中性粒细胞的寿命进行直接测量。
