Wilson M E, Bronson P M, Hamilton R G
Department of Oral Biology, School of Dental Medicine, State University of New York at Buffalo 14214.
Infect Immun. 1995 Mar;63(3):1070-5. doi: 10.1128/iai.63.3.1070-1075.1995.
Sera from patients with localized juvenile periodontitis (LJP) often contain markedly elevated levels of immunoglobulin G2 (IgG2) antibodies reactive to cell envelope constituents of Actinobacillus actinomycetemcomitans. The objective of this study was to determine if these IgG2 antibodies are capable of supporting phagocytosis and killing of A. actinomycetemcomitans by human neutrophils. Polyclonal IgG2 antibodies were prepared from high-titer LJP serum by affinity chromatography, yielding a preparation which was > 99% subclass restricted and retained immunoreactivity to A. actinomycetemcomitans antigens. Affinity-purified IgG2 antibodies were evaluated by an in vitro opsonophagocytic assay that employed neutrophils obtained from donors who were homozygous for the H131 allotype of Fc gamma receptor type IIa (CD32), which efficiently binds human IgG2 antibodies. Affinity-purified IgG2 antibodies from LJP serum but not from sera of periodontally healthy individuals promoted phagocytosis and killing of A. actinomycetemcomitans. The expression of IgG2-dependent opsonic activity required the presence of complement. Incubation of A. actinomycetemcomitans with neutrophils in the presence of an optimal concentration of LJP IgG2 (50 micrograms/ml) and 5% hypogammaglobulinemic serum (as a complement source) resulted in a > 1 log10 reduction in bacterial viability within 30 min. The opsonic activity of IgG2 antibodies was found to be comparable to that observed with affinity-purified IgG1 antibodies. Moreover, IgG1 antibodies interacted synergistically with IgG2 antibodies in promoting opsonophagocytosis of A. actinomycetemcomitans. The results of this study indicate that LJP serum contains IgG2 antibodies which, when employed in conjunction with neutrophils that express Fc gamma receptors capable of recognizing this subclass, are opsonic for A. actinomycetemcomitans.
局限性青少年牙周炎（LJP）患者的血清中，免疫球蛋白G2（IgG2）抗体对伴放线放线杆菌细胞包膜成分的反应水平通常显著升高。本研究的目的是确定这些IgG2抗体是否能够促进人类中性粒细胞对伴放线放线杆菌的吞噬和杀灭作用。通过亲和层析从高滴度LJP血清中制备多克隆IgG2抗体，得到的制剂> 99%为亚类限制性，且对伴放线放线杆菌抗原保持免疫反应性。通过体外调理吞噬试验评估亲和纯化的IgG2抗体，该试验采用从Fcγ受体IIa型（CD32）H131同种异型纯合供体获得的中性粒细胞，其能有效结合人类IgG2抗体。来自LJP血清而非牙周健康个体血清的亲和纯化IgG2抗体促进了对伴放线放线杆菌的吞噬和杀灭。IgG2依赖性调理活性的表达需要补体的存在。在最佳浓度的LJP IgG2（50微克/毫升）和5%低丙种球蛋白血症血清（作为补体来源）存在的情况下，将伴放线放线杆菌与中性粒细胞一起孵育，30分钟内细菌活力降低> 1个对数10。发现IgG2抗体的调理活性与亲和纯化的IgG1抗体观察到的活性相当。此外，IgG1抗体在促进伴放线放线杆菌的调理吞噬作用方面与IgG2抗体协同作用。本研究结果表明，LJP血清含有IgG2抗体，当与能够识别该亚类的Fcγ受体表达的中性粒细胞联合使用时，对伴放线放线杆菌具有调理作用。
