Goldblatt D
Immunobiology Unit, Institute of Child Health, London, UK.
Dev Biol Stand. 1998;95:125-32.
Maturation of the adaptive immune system occurs early in development and by 14 weeks gestation the developing foetus has circulating differentiated T cells and B cells capable of responding to antigen. While the immune system is capable of responding appropriately at birth to protein antigens, its capacity to respond to carbohydrates is limited. A consequence of this is the success of bacteria with carbohydrate capsules in causing invasive paediatric infections. Vaccines containing purified carbohydrates alone are thus limited in their immunogenicity and fail to provide protection for those most at risk. Conjugate vaccine technology, where a carbohydrate antigen is chemically coupled to a protein carrier, has overcome the limitation of carbohydrates as vaccine antigens. The first such vaccine to enjoy widespread use, the Haemophilus influenzae type b conjugate vaccines, have met with enormous success and have almost eradicated invasive Hib disease in those countries where their use in infancy is routine. Conjugate technology is thus being applied to a number of other vaccines in development, including Neisseria meningitidis groups A and C and Streptococcus pneumoniae vaccines.
适应性免疫系统的成熟在发育早期就已发生，到妊娠14周时，发育中的胎儿体内已存在能够对抗原作出反应的循环分化T细胞和B细胞。虽然免疫系统在出生时能够对蛋白质抗原作出适当反应，但其对碳水化合物的反应能力有限。其结果是，带有碳水化合物荚膜的细菌在引发侵袭性儿科感染方面很成功。因此，仅含纯化碳水化合物的疫苗免疫原性有限，无法为高危人群提供保护。将碳水化合物抗原与蛋白质载体化学偶联的结合疫苗技术，克服了碳水化合物作为疫苗抗原的局限性。首个广泛使用的此类疫苗——b型流感嗜血杆菌结合疫苗，取得了巨大成功，在婴儿期常规使用该疫苗的国家，侵袭性b型流感嗜血杆菌疾病几乎已被根除。因此，结合疫苗技术正被应用于其他一些正在研发的疫苗，包括A群和C群脑膜炎奈瑟菌疫苗以及肺炎链球菌疫苗。
