The actions of immune cells within the kidney are of fundamental importance in kidney homeostasis and disease. In disease settings such as acute kidney injury, anti-neutrophil cytoplasmic antibody-associated vasculitis, lupus nephritis and renal transplant rejection, immune cells resident within the kidney and those recruited from the circulation propagate inflammatory responses with deleterious effects on the kidney. As in most forms of inflammation, intravital imaging — particularly two-photon microscopy — has been critical to our understanding of immune cell responses in the renal microvasculature and interstitium, enabling visualization of immune cell dynamics over time rather than statically. These studies have demonstrated differences in the recruitment and function of these cells from those in more conventional vascular beds, and provided a wealth of information on the actions of blood-borne immune cells such as neutrophils, monocytes and T cells, as well as kidney-resident mononuclear phagocytes, in a range of diseases affecting different kidney compartments. In particular, in vivo imaging has furthered our understanding of leukocyte function within the glomerulus in acute glomerulonephritis, and in the tubulointerstitium and interstitial microvasculature during acute kidney injury and following transplantation, revealing mechanisms of immune surveillance, antigen presentation and inflammation in the kidney.

肾脏内免疫细胞的作用对于肾脏稳态和疾病至关重要。在急性肾损伤、抗中性粒细胞胞质抗体相关血管炎、狼疮性肾炎和肾移植排斥反应等疾病环境中，驻留在肾脏内的免疫细胞和从循环中募集的免疫细胞会传播炎症反应，对肾脏产生有害影响。与大多数形式的炎症一样，活体成像——尤其是双光子显微镜——对于我们理解肾脏微血管系统和间质中的免疫细胞反应至关重要，能够随着时间的推移而不是静态地观察免疫细胞动态。这些研究表明，这些细胞与更传统的血管床中的细胞在募集和功能方面存在差异，并提供了大量关于血源性免疫细胞（如中性粒细胞、单核细胞和 T 细胞）以及肾脏驻留的单核吞噬细胞在影响不同肾脏隔室的一系列疾病中的作用的信息。特别是，体内成像进一步加深了我们对急性肾小球肾炎肾小球内白细胞功能的理解，以及急性肾损伤和移植后肾小管间质和间质微血管系统中白细胞功能的理解，揭示了免疫监视、抗原呈递和肾脏炎症的机制。