Attwood J T, Williams Y, Feighery C
Immunology Department, St. James's Hospital, Dublin, Ireland.
Acta Paediatr. 2001 Jan;90(1):99-101. doi: 10.1080/080352501750064969.
Homozygous deficiency of the second component of complement (C2) is the most common inherited deficiency of complement. Although C2 deficiency has been detected in asymptomatic individuals, patients usually present with either autoimmune disease or recurrent pyogenic infection, particularly due to encapsulated bacteria such as Streptococcus pneumoniae, Haemophilus influenzae type b and Neisseria meningitidis. Interestingly, infection is the most common mode of presentation of C2 deficiency in young children (1). An association between C2 deficiency and IgG subclass deficiency has also been previously described. We now report a female child with C2 deficiency that presented at the age of 3 mo with recurrent pneumococcal septicaemia. Although IgG subclass levels were normal, specific IgG responses to vaccination against S. pneumoniae and H. influenzae were significantly impaired.
补体第二成分（C2）纯合子缺陷是最常见的遗传性补体缺陷。虽然在无症状个体中已检测到C2缺陷，但患者通常表现为自身免疫性疾病或复发性化脓性感染，特别是由肺炎链球菌、b型流感嗜血杆菌和脑膜炎奈瑟菌等包膜细菌引起的感染。有趣的是，感染是幼儿C2缺陷最常见的表现形式（1）。此前也有关于C2缺陷与IgG亚类缺陷之间关联的描述。我们现在报告一名患有C2缺陷的女童，她在3个月大时出现复发性肺炎球菌败血症。尽管IgG亚类水平正常，但针对肺炎链球菌和流感嗜血杆菌疫苗接种的特异性IgG反应明显受损。
