IMMUNE RESPONSE TO POLYSACCHARIDE AND CONJUGATE VACCINES

对多糖(PS)抗原的免疫反应是高度调节的 并且具有包括受限子类在内的几个区别特征， 可变区基因使用，良好的特异性和亲和力。简单PS备注 与蛋白质结合(如C群脑膜炎奈瑟氏菌(MCPS)) 诱导胸腺非依赖性(TI)反应。PS与蛋白质的偶联 (例如与破伤风类毒素偶联的MCPS(MCPS-TT))，另一方面， 引发一种不同类型的反应，称为胸腺依赖(TD)。 以往对抗MCPS单抗的分析表明，VH基因家族的用途是 由VHJ558主导。抗体亲和力可能是一个重要的决定因素 应该被认为和集中注意力一样重要 在评估接种疫苗的抗体反应方面。因此，免疫球蛋白A、免疫球蛋白 从3块试板中纯化出IgM单抗，并进行亲和力测定 荧光酶联免疫吸附试验检测纯化PS结合的定量方法 (Felisa)试验。两组单抗(C2和CP)一般都有2个目 50%结合的浓度较低，表明 Td mAb的亲和力显著高于Td mAb(10-100倍) 反MCPS。MAb在凝胶中沉淀PS的能力也很强。 研究并与由确定的特异性良好地关联 定量的费利萨。正在进行的序列分析将确定 体细胞突变可以解释亲和力的增加。 我们实验室早期的小鼠模型研究表明， 即使作为TD给药，对MCPS的免疫应答也会延迟 MCPS-TT结合物。因此，进行了研究，以检查是否 新生小鼠TD结合物反应延迟是由于缺陷 抗原呈递。作为第一步，TT和MCPS-TT反应性助手T 用MCPS-TT免疫小鼠，获得细胞克隆。 T细胞克隆即P1/7、P4/19、P4/20和P4/40用于 确定与TT呈递有关的抗原提呈细胞 或MCPS-TT。结果表明，成人B细胞要多得多 对T细胞提呈TT或MCPS-TT的效果优于总脾细胞 或者巨噬细胞。B细胞向T细胞递呈TT或MCPS-TT的能力 T细胞克隆率是脾细胞总数的4~6倍。成人B细胞 也被发现比浓缩的效率高几倍 巨噬细胞呈递这些抗原。然而，成体树突状细胞 被发现是这个系统中最有效的抗原提呈细胞 其效率约为B细胞的2倍。进一步研究 将研究抗原特异性B细胞在这一过程中的作用。

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 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). Previous analyses of anti-MCPS mAb reveal that VH gene family usage is dominated by VHJ558. Antibody affinity may be an important determinant of host defense and should be considered as important as concentration in evaluating antibody response to vaccination. Therefore the IgA, IgG and IgM mAbs from the 3 panels were purified and tested for avidity by a quantitative measure of binding to purified PS in a fluorescent ELISA (FELISA) assay. Both panels of mAbs (C2 and CP), in general, had 2 orders of magnitude lower concentrations for 50% binding, indicating that the TD mAb were of significantly higher avidity (10-100 fold higher) than the anti-MCPS. The ability of the mAb to precipitate PS in gel were also studied and correlated well with the specificity determined by quantitative FELISA. Sequence analysis in progress will determine if somatic mutation can account for the increased avidity . 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. Therefore, studies were undertaken to examine whether the delay in response TD conjugates in neonatal mice is due to defective antigen presentation. As a first step, TT and MCPS-TT reactive helper T cell clones were generated from mice that were immunized with MCPS-TT. The T cells clones namely P1/7, P4/19, P4/20 and P4/40 were used to identify the antigen presenting cells involved in the presentation of TT or MCPS-TT. The results showed that adult B cells were much more effective in presenting TT or MCPS-TT to T cells than total spleen cells or macrophages. The ability of B cells to present TT or MCPS-TT to the T cell clones were 4-6 fold higher than total splenocytes. Adult B cells were also found to be several fold more efficient than enriched macrophages in presenting these antigen. However, adult dendritic cells were found to be most effective antigen presenting cells in this system and the efficiency was about 2-fold higher than B cells. Further studies will examine the role of antigen-specific B cells in this process.