IGG2, A.A. AND RISK FOR LOCALIZED JUVENILE PERIODONTITIS

中性粒细胞显示出很强的杀菌活性 伴生放线杆菌(A.A.)，但仅在 特异性免疫球蛋白抗体。局限性青少年牙周炎(LJP)研究对象 产生大量的针对这种微生物的IgG2抗体。这个 IgG2支持A.A吞噬的能力。可能会受到 吞噬细胞免疫球蛋白Fc受体结合这一亚类的能力。FcgRII， 中性粒细胞上存在主要的Ig G Fc受体，表现为 基因定义的结构多态显著影响 IgG2结合。一个同种异型，在131位含有组氨酸(H)， 有效地结合IgG2，而含有精氨酸(R)的同种异型 这一立场并不适用。在目前的研究中，与马克博士合作 Wilson，我们在两个LJP家系中确定了FcgRIIA等位基因。FcgRILA 用聚合酶链式反应从基因组DNA中扩增出FcgRIIA基因 使用等位基因特异的寡核苷酸探针分析来确定。严重性 牙周病的诊断是通过牙槽骨的放射学损失来确定的 骨头和探头深度。LJP最严重的三个病例显示 R/R基因型，两例LJP术后患者也是如此。另外两个LJP 表现为不太严重的疾病的患者表现出 H/R基因分型。其余的受试者，没有表现出LJP，是H/R。 这些初步结果表明，罹患糖尿病的风险增加 LJP可能是由于大量生产的独特组合 抗A.A的IgG2抗体的量。以及减少的频率 FcgRIIA基因H等位基因的表达

Neutrophils display potent bactericidal activity toward Actinobacillus actinomycetemcomitans (A.a.), but only in the presence of specific IgG antibody. Localized juvenile periodontitis (LJP) subjects produce substantial amounts of IgG2 antibody against this organism. The ability of IgG2 to support phagocytosis of A.a. may be limited by the capacity of phagocyte IgG Fc receptors to bind this subclass. FcgRII, the main IgG Fc receptor present on neutrophils, exhibits a genetically-defined structural polymorphism which significantly affects IgG2 binding. One allotype, which contains histidine (H) at position 131, binds IgG2 efficiently, whereas the allotype containing arginine (R) at this position does not. In the present study, working with Dr. Mark Wilson, we determined FcgRIIA allotype in two families with LJP. FcgRILA was amplified from genomic DNA by PCR, after which FcgRIIA genotype was determined using an allele-specific oligonucleotide probe assay. Severity of periodontal disease was determined by radiographic loss of alveolar bone and by probing depth. The three most severe cases of LJP exhibited the R/R genotype, as did two post-LJP patients. The other two LJP patients, presenting with a less severe form of the disease, demonstrated H/R genotypes. The remaining subject, who did not exhibit LJP, was H/R. These preliminary results suggest that increased risk for development of LJP may be due to a unique combination of production of substantial amounts of IgG2 antibodies against A .a. and a decreased frequency of expression of the H allele of FcgRIIA.