Regulation of Immune Response to Polysaccharides

对多糖的免疫反应的调节

• 批准号: 6545881
• 负责人: KE E STEIN
• 金额: --
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6545881
• 关键词: antibacterial antibody; antibody formation; antibody specificity; bacterial antigens; bacterial polysaccharides; bacterial vaccines; bactericidal immunity; biological models; chemical conjugate; chemical structure function; developmental immunology; genetic recombination; genetically modified animals; immunogenetics; immunoglobulin genes; immunoregulation; immunotherapy; laboratory mouse; nonhuman therapy evaluation; site directed mutagenesis

Summary: The immune response to polysaccharide (PS) antigens is highly regulated and has several distinguishing features including restricted subclass, variable region gene usage, fine specificity, and avidity. Simple PS not conjugated to protein (such as bacterial Levan (BL, Neisseria meningitidis group C (MCPS)) elicit a thymus-independent (TI) response. PS conjugated to proteins (such as MCPS coupled to tetanus toxoid, (MCPS-TT)), on the other hand, elicit a different type of response, termed thymus-dependent (TD). Our earlier analysis of anti-BL antibodies had shown a germline primary response to the inulin (In) branch determinants. Two injections of BL, however, elicited IgM mAb with somatic mutations and higher affinity. We have now performed site-directed mutagenesis of the germline antibodies and identified specific sites resulting in higher or lower affinity. Data show the importance of aromatic and basic amino acids in the CDRs of anti-PS antibodies. In our analysis of the regulation of diversity in the anti-In response we have mapped the Sr1 diversity gene to mouse chromosome 14. Recent studies in TCR KO mice have shown that the response to In is not only TI, but is not influenced by T cells when added back, despite a large increase in serum IgG and IgM. Previous analyses of anti-MCPS and anti-MCPS TT mAb reveal that VH gene family usage is dominated by VHJ558. Sequence analysis of anti MCPS mAb shaows that several different germline genes are used in this response, even by mAb of the same fine specificity. Few somatic mutations are seen in response to MCPS, but when observed, correlate with an increase in affinity. Recent modeling studies suggest that the presence of basic amino acids in the combining site aslo correlate with an increase in affinity. Earlier mouse model studies in our laboratory indicated a developmental delay in the immune response to MCPS even when it was administered as TD MCPS-TT conjugates. As part of these studies, T cell clones were generated from mice immunised with MCPS TT. These clones have been shown to include specificities for MCPS and the PS reactive clones have now been characterized as to their requirements for MHC and for accessory cells. The data suggest that not only B cells, but also PS reactive T cells may contribute to the protective stimulation of neonatal responses to conjugate vaccines. One of the goals of the Children's Vaccine Initiative is to reduce the number of contacts required to immunize a child fully. To meet this goal several combined vaccines have been tested for their safety and immunogenicity in infants. We have developed a model in SW outbred mice to examine the effects of combining vaccines on the response to individual components. We initially observed that DTaP interferes with the anti-Hib response to Hib-TT Subsequent studies have confirmed the earlier findings but the interference from DTaP is not significant. We also observed that Hib-TT interfered with the response to all three types of polio, given as IPV. These studies have been repeated in inbred BALB/c mice and confirm the interference with poliotiters by Hib-TT. Preliminary studies suggest that anothe Hib conjugate, Hib-CRM197, does not cause this interference.

摘要：多糖（PS）抗原的免疫应答受到高度调控，具有限制亚类、可变区域基因使用、精细特异性和亲切性等特点。未与蛋白结合的简单PS（如Levan细菌（BL）、C组脑膜炎奈瑟菌（MCPS））可引起胸腺非依赖性（TI）反应。另一方面，与蛋白质结合的PS（如MCPS与破伤风类毒素（MCPS- tt）结合）会引起一种不同类型的反应，称为胸腺依赖性（TD）。我们早期的抗bl抗体分析显示，菊粉（In）分支决定因子对种系有初级反应。然而，两次注射BL引发了具有体细胞突变和更高亲和力的IgM单抗。我们现在已经对种系抗体进行了定点诱变，并确定了导致更高或更低亲和力的特定位点。数据显示芳香和碱性氨基酸在抗ps抗体cdr中的重要性。在我们对抗-In反应多样性调控的分析中，我们将Sr1多样性基因定位到小鼠14号染色体上。最近对TCR KO小鼠的研究表明，尽管血清IgG和IgM大量增加，但对in的反应不仅仅是TI，而且当重新加入时不受T细胞的影响。此前对抗mcps和抗mcps TT单抗的分析表明，VH基因家族主要由VHJ558使用。抗MCPS单抗的序列分析表明，在这种反应中使用了几种不同的种系基因，即使是具有相同精细特异性的单抗。很少有体细胞突变在MCPS反应中被观察到，但当观察到时，与亲和力的增加相关。最近的建模研究表明，碱性氨基酸在结合位点的存在也与亲和力的增加有关。我们实验室早期的小鼠模型研究表明，即使将MCPS作为TD MCPS- tt结合物施用，对MCPS的免疫反应也会出现发育迟缓。作为这些研究的一部分，用MCPS TT免疫的小鼠产生了T细胞克隆。这些克隆已被证明包括MCPS的特异性，PS反应性克隆现在已被表征为它们对MHC和辅助细胞的需求。数据表明，不仅B细胞，而且PS反应性T细胞可能有助于新生儿对结合疫苗反应的保护性刺激。儿童疫苗倡议的目标之一是减少对儿童进行全面免疫所需的接触次数。为了实现这一目标，已经对几种联合疫苗的安全性和婴儿免疫原性进行了测试。我们在SW近交小鼠中建立了一个模型，以检查组合疫苗对单个成分的反应的影响。我们最初观察到DTaP干扰Hib-TT的抗hib反应，随后的研究证实了早期的发现，但DTaP的干扰并不显著。我们还观察到Hib-TT干扰了对所有三种脊髓灰质炎的反应，称为IPV。这些研究已在近亲繁殖的BALB/c小鼠中重复，并证实Hib-TT对脊髓灰质炎患者的干扰。初步研究表明，另一种Hib偶联物Hib- crm197不会引起这种干扰。