Tolo K, Helgeland K
Institute of Microbiology, University of Oslo, Norway.
Oral Microbiol Immunol. 1991 Dec;6(6):373-7. doi: 10.1111/j.1399-302x.1991.tb00509.x.
Actinobacillus actinomycetemcomitans (ATCC 33384) can produce and release components that bind to the Fc part of IgG. Fc-binding components were observed in whole bacteria, capsular material and medium from broth cultures. The components were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotted with biotinylated Fc-fragments and myeloma proteins. In a phagocytosis assay with human granulocytes and sheep erythrocytes, preincubation of opsonized erythrocytes with protein A reduced phagocytosis by 90%. In contrast, preincubation of the opsonizing antibody with medium components from a culture of A. actinomycetemcomitans enhanced the opsonizing effect of the antibody. The enhanced binding of erythrocytes may be caused by formation of aggregates between opsonizing antibody and bacterial Fc-binding components. Aggregated IgG can bind to low-affinity Fc gamma II and gamma III receptors that cannot bind monomeric IgG. Release of Fc-binding components from bacteria may contribute to the periodontal lesion through interference with the phagocytic activity of granulocytes and with the complement system. Fc-binding components may also interfere with downregulation of the B-cell response.
伴放线放线杆菌（ATCC 33384）能够产生并释放与IgG的Fc部分结合的成分。在全菌、荚膜物质以及肉汤培养物的培养基中均观察到了Fc结合成分。这些成分通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳进行分离，并用生物素化的Fc片段和骨髓瘤蛋白进行免疫印迹分析。在用人粒细胞和绵羊红细胞进行的吞噬试验中，用蛋白A对调理后的红细胞进行预孵育可使吞噬作用降低90%。相比之下，用伴放线放线杆菌培养物的培养基成分对调理抗体进行预孵育可增强抗体的调理作用。红细胞结合增强可能是由于调理抗体与细菌Fc结合成分之间形成了聚集体。聚集的IgG可与无法结合单体IgG的低亲和力FcγII和γIII受体结合。细菌释放的Fc结合成分可能通过干扰粒细胞的吞噬活性和补体系统而导致牙周病变。Fc结合成分也可能干扰B细胞反应的下调。
