Department of Medicine, Brigham & Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Annu Rev Immunol. 2010;28:107-30. doi: 10.1146/annurev-immunol-030409-101159.
The capsular polysaccharides (CPSs) of most pathogenic bacteria are T cell-independent antigens whose conjugation to carrier proteins evokes a carbohydrate-specific response eliciting T cell help. However, certain bacterial CPSs, known as zwitterionic polysaccharides (ZPSs), activate the adaptive immune system through processing by antigen-presenting cells and presentation by the major histocompatibility complex class II pathway to CD4(+) T cells. This discovery was the first mechanistic insight into how carbohydrates-a class of biological molecules previously thought to be T cell independent-can in fact activate T cells. Through their ability to activate CD4(+) T cells, ZPSs direct the cellular and physical maturation of the developing immune system. In this review, we explore the still-enigmatic relations between CPSs and the adaptive immune machinery at the cellular and molecular levels, and we discuss how new insights into the biological impact of ZPSs expand our concepts of the role of carbohydrates in microbial interactions with the adaptive immune system.
大多数病原菌的荚膜多糖（CPS）是 T 细胞非依赖型抗原，与载体蛋白结合可引发针对碳水化合物的特异性反应，从而募集 T 细胞辅助。然而，某些被称为两性离子多糖（ZPS）的细菌 CPS 通过抗原呈递细胞的加工以及主要组织相容性复合体 II 途径呈递至 CD4+T 细胞，激活适应性免疫系统。这一发现首次揭示了碳水化合物（一类曾被认为是 T 细胞非依赖型的生物分子）实际上如何激活 T 细胞的机制。通过激活 CD4+T 细胞，ZPS 指导着正在发育的免疫系统的细胞和物理成熟。在这篇综述中，我们探讨了 CPS 与适应性免疫机制在细胞和分子水平上的仍然神秘的关系，并讨论了对 ZPS 生物学影响的新认识如何扩展我们对碳水化合物在微生物与适应性免疫系统相互作用中作用的概念。
