整合素介导微泡声学造影剂与白细胞粘附的实验研究

目的:研究白细胞与蛋白微泡声学造影剂的粘附过程及机制。方法:光镜和电镜观察离体不同状态下的白细胞与蛋白微泡的粘附过程,流式细胞仪测定白细胞与微泡混合后,在存在或缺乏白细胞整合素的情况下,荧光强度的变化。结果:蛋白微泡与PMA激活的白细胞接触后 5min大量结合到白细胞表面,未经激活的白细胞表面少有微泡粘附 (20.30±2. 67vs4.50±1.43,P <0.01)。15min时微泡被吞噬入细胞内,并保持形态完整至 30min。两者的结合可被Mac-1mAb大部分阻止 (P <0.01),VLA-4mAb轻度阻止 (P <0.05)。结论:蛋白微泡声学造影剂可经 β₂ 整合素Mac-1和VLA-4介导与激活的白细胞结合,并进入细胞内从而在炎症部位停留,保持形态完整约15min,仍不失声学活性

Study on integrin-mediated albumin microbubbles adherence to activated leukocytes

AIM:To investigate the mechanism responsible for albumin microbubbles adherence to activated leukocytes. METHODS: In vitro studies were performed in which activated or nonactivated leukocytes were incubated with albumin microbubbles and observed under microscopy. The suspensions of leukocytes and microbubbles which contained or absented of integrins were analyzed with flow cytometry.RESULTS: A minimum of 50cells were identified under transillumination. 5 min after microbubbles were incubated with leukocytes, the number of cells interacting with microbubbles was greater for activated cells than for nonactivated cells(20.30±2.67 vs 4.50±1.43, P <0.01).Microbubbles attached to the surface of activated leukocytes were phagocytosed and remained intact for up to 30min. Microbubble attachment was inhibited notably by blocking the leukocyte β₂-integrin Mac-1(P <0.01) and by VLA-4mAb slightly(P <0.05) CONCLUSION: The mechanism of albumin microbubbles attaching to and phagocytosed by leukocytes was due to β₂-integrin and VLA-4 mediation. Phagocytosed microbubbles can remain at the regions of inflammation for15 min, also responsible to ultrasound.