Shackelford P G, Nelson S J, Palma A T, Nahm M H
Edward Mallinckrodt Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110.
J Immunol. 1988 May 1;140(9):3200-5.
To investigate immuno-incompetence to polysaccharide Ag in young children, antibodies to the polysaccharide and protein Ag of Streptococcus pyogenes were studied. S. pyogenes was chosen because it commonly causes natural infections and has well-characterized polysaccharide and protein Ag. In children over the age of 2 yr it was found that the maturation of antibody responses to the polysaccharide Ag of S. pyogenes (A-CHO) appeared to occur in parallel with, or even earlier, than the responses to streptococcal protein Ag. When antibodies to group A carbohydrate (A-CHO) were studied in detail, qualitative differences between the antibodies of children and adults were demonstrated. Although anti-A-CHO antibodies of adults were strikingly restricted to the IgG2 subclass, those of children were found in both the IgG1 and IgG2 subclasses. In addition, the clonal diversity of IgG antibodies to A-CHO increased with age, and additional clonotypes were detectable in convalescent sera of some subjects of all ages after infection. Two cases with major additional clonotypes after group A streptococcal infection were studied in detail. In these two cases the additional clonotypes belonged to a different IgG subclass than the previously dominant clonotypes, and the expression of the additional major clonotypes occurred in both IgG1 and IgG2 subclasses.
为研究幼儿对多糖抗原的免疫无反应性，对化脓性链球菌的多糖和蛋白质抗原的抗体进行了研究。选择化脓性链球菌是因为它通常引起自然感染，并且具有特征明确的多糖和蛋白质抗原。在2岁以上的儿童中发现，对化脓性链球菌多糖抗原（A-CHO）的抗体反应成熟似乎与对链球菌蛋白质抗原的反应同时发生，甚至更早。当详细研究抗A组碳水化合物（A-CHO）抗体时，发现儿童和成人抗体之间存在质的差异。虽然成人的抗A-CHO抗体明显局限于IgG2亚类，但儿童的抗A-CHO抗体在IgG1和IgG2亚类中均有发现。此外，抗A-CHO IgG抗体的克隆多样性随年龄增加，并且在所有年龄段的一些受试者感染后的恢复期血清中可检测到额外的克隆型。对两例A组链球菌感染后出现主要额外克隆型的病例进行了详细研究。在这两例病例中，额外的克隆型属于与先前占主导地位的克隆型不同的IgG亚类，并且额外的主要克隆型在IgG1和IgG2亚类中均有表达。
