De La Cruz C, Haimovich B, Greco R S
Department of Surgery, UMDNJ-Robert Wood Johnson Medical School, New Brunswick, New Jersey, 08903, USA.
J Surg Res. 1998 Nov;80(1):28-34. doi: 10.1006/jsre.1998.5262.
The infection of a vascular prosthesis is a dreaded clinical outcome. Since fibrinogen (FBGN) and immunoglobulin (IgG) coat the implanted biomaterial surface, it is with these immobilized proteins that the neutrophil (PMN) interacts. This study tests the hypothesis that PMN are impaired in their ability to kill bacteria when bound to immobilized IgG or FBGN. Isolated human PMN were bound to FBGN or IgG and then left untreated or exposed to phorbol myristate acetate (PMA; 10(-7) M). PMN adhered loosely, but did not spread, onto FBGN. In contrast, PMN spread fully onto IgG, exhibiting polarized pseudopodia. PMA treatment induced spreading of the FBGN bound cells. Suspended and adherent PMN were incubated 1 h with 14C-labeled Staphylococcus aureus; then, phagocytosis was assessed by radioactive uptake or bacterial kill was determined by plating recovered bacteria and colony counting. Data were analyzed by unpaired t test. We observed that both the phagocytic and the killing ability of FBGN-bound PMN were similar to that of suspended PMN. Conversely, IgG-bound PMN displayed a 62 +/- 6% (P < 0.01) decrease in phagocytosis and 33 +/- 7% (P < 0.05) reduction in kill vs suspended cells. PMA induced a 74 +/- 6% (P < 0.01) reduction in phagocytosis and 68 +/- 5% (P < 0.01) reduction in kill of bacteria for PMN bound to FBGN with no further effect on IgG-bound PMN. Using fluorescent vital dyes and confocal microscopy we determined that 33% fewer PMN were engaged in phagocytosis when bound to IgG vs FBGN. We conclude that Fc receptor ligation by immobilized IgG or PMA treatment of the FBGN-adherent PMN triggers cell spreading and reduced bactericidal activity. These results indicate that excessive cytoskeletal organization may impair the ability of PMN to kill bacteria and result in vascular graft infections.
血管假体感染是一种可怕的临床结果。由于纤维蛋白原（FBGN）和免疫球蛋白（IgG）覆盖植入生物材料表面，中性粒细胞（PMN）正是与这些固定化蛋白相互作用。本研究检验了这样一个假设，即当PMN与固定化IgG或FBGN结合时，其杀菌能力会受损。分离出的人PMN与FBGN或IgG结合，然后不进行处理或暴露于佛波酯（PMA；10⁻⁷ M）。PMN松散地黏附在FBGN上，但不会铺展。相反，PMN完全铺展在IgG上，呈现出极化伪足。PMA处理可诱导与FBGN结合的细胞铺展。将悬浮和黏附的PMN与¹⁴C标记的金黄色葡萄球菌孵育1小时；然后，通过放射性摄取评估吞噬作用，或通过接种回收细菌并进行菌落计数来测定杀菌能力。数据采用非配对t检验进行分析。我们观察到，与FBGN结合的PMN的吞噬和杀菌能力与悬浮的PMN相似。相反，与IgG结合的PMN相比悬浮细胞，吞噬作用降低了62±6%（P<0.01），杀菌能力降低了33±7%（P<0.05）。PMA使与FBGN结合的PMN的吞噬作用降低了74±6%（P<0.01），杀菌能力降低了68±5%（P<0.01），而对与IgG结合的PMN没有进一步影响。使用荧光活性染料和共聚焦显微镜，我们确定与IgG结合时参与吞噬作用的PMN比与FBGN结合时少33%。我们得出结论，固定化IgG的Fc受体连接或对与FBGN黏附的PMN进行PMA处理会触发细胞铺展并降低杀菌活性。这些结果表明，过度的细胞骨架组织可能会损害PMN的杀菌能力，并导致血管移植物感染。
