犬体外循环后中性粒细胞功能变化的研究

目的 研究体外循环后是否存在中性粒细胞的黏附和破坏能力增强,而吞噬杀菌能力减弱的现象.方法 健康成年狼犬12只,随机均分为体外循环(CPB)组和假CPB(Sham)组,CPB组转机100 min后停机;Sham组静置100 min.通过测定CPB后中性粒细胞CD11b/CD18的表达、肺组织髓过氧化物酶(MPO)含量和肺功能等,评估中性粒细胞的黏附功能和对组织的破坏作用;通过测定中性粒细胞吞噬功能、细胞内MPO检测等,评估中性粒细胞的免疫功能.结果 CPB后4 h,CPB组中性粒细胞CD11b、CD18的表达和肺组织MPO活性显著高于肝素化前和Sham组(55±21)IU/100 g组织vs(30±19)IU/100 g组织,均P<0.01],而PaO2/FiO2显著低于肝素化前和Sham组(319±79 vs 405±101,均P<0.05).细胞的超微结构显示,CPB组中性粒细胞伸出粗大触角.伴随中性粒细胞黏附功能的升高,CPB组中性粒细胞的吞噬功能显著低于体外循环前和对照组(129±53 vs357±92,均P<0.05).但两组动物MPO积分差异无统计学意义.经IL-8刺激后,中性粒细胞MPO释放和氧自由基产生差异无统计学意义(均P>0.05).结论 体外循环能导致中性粒细胞功能失调,包括黏附能力的提高和吞噬功能的下降,这可能是导致体外循环后器官损伤和感染率增加的主要原因.

Changes of neutrophil functions after cardiopulmonary bypass: experiment with dogs

OBJECTIVE: To investigate if increase of adhesion function and capability to destroy and decrease of phagocytosis of neutrophils occur after cardiopulmonary bypass (CPB). METHODS: 12 mongrel dogs were randomly divided into two equal groups: CPB group, weaned from CPB after 100 min of CPB; and sham group standing for 100 min without CPB. All dogs were observed for another 4 hrs. Blood samples were collected from the femoral vein before heparinization and by the end of experiment to measure the white blood cell count and classification, and expression of CD11b and CD18. Tissue samples of the right and left lungs were collected before heparinization and by the end of experiment. The expression of CD11b/CD18 in neutrophils, myeloperoxidase (MPO) activities in lung tissue, and pulmonary function were determined to access the adhesion function of neutrophils and the injuries to tissues. The phagocytotic activities, the release of MPO and the generation of oxygen free radical induced by IL-8 were surveyed to access the immune function of neutrophils. RESULTS: The fluorescence level of CD11b of the neutrophils in the CPB group was (2675 +/- 479) and the fluorescence level of CD18 of the neutrophils was (1574 +/- 262), both significantly higher than those before heparinization and those of the sham group (all P < 0.05). Four hours after CPB, the MPO activity of lung tissue of the CPB group was (55.02 +/- 21.04 U/100 g wet tissue), significantly higher than those before heparinization and that of the sham group (both P < 0.05); the ratios of PaO2/FiO2 of the CPB group was (319 +/- 79), significantly lower than those before heparinization and that of the sham group (both P < 0.05). Transmission electron microscopic examination revealed tentacle protrusion on the neutrophil in the CPB group, while the neutrophils were intact in the sham group. Contrary to the increase of adhere function, the numbers of neutrophil with phagocytic function of the CPB group was 35% +/- 11%, significantly lower than that of the sham group (74% +/- 9%, P < 0.01) the number of bacteria phagocytized by neutrophils per ml blood of the CPB group was (1484 +/- 238 ), significantly lower than that of the sham group (3106 +/- 714). There were no differences in the accumulated points of MPO in neutrophils, release of MPO, and generation of oxygen free radical between these 2 groups. CONCLUSION: CPB causes neutrophil function disorder, including increase of adhesion function and reduction of phagocytic function.