Eibl M
Kinderarztl Prax. 1989 Sep;57(9):419-28.
Serum IgG contains 4 subclasses, IgG1 (60-66%), IgG2 (20-30%), IgG3 (less than or equal to 5%) and IgG4. Individual subclasses vary with respect to their physicochemical and biological properties. IgG subclass concentrations in serum are age dependent. IgG1 and IgG3 reach near to adult levels around the age of 3, IgG2 and IgG4 after the age of 6. Antibodies of certain specificities generally belong to a certain isotype (subclass) due to the isotype restriction. Patients with subclass deficiencies often suffer from recurrent infections. Those with IgG2 deficiency coften occurring with IgA and IgG4 deficiency) develop recurrent infection of the upper and lower respiratory tract often caused by pyogenic microorganisms (Haemophilus, Pneumo-(occus). Since early initiation of IVIG substitution therapy has a beneficial effect on long term prognosis the importance of early diagnosis is apparent.
血清IgG包含4个亚类，即IgG1（60 - 66%）、IgG2（20 - 30%）、IgG3（小于或等于5%）和IgG4。各个亚类在物理化学和生物学特性方面存在差异。血清中IgG亚类浓度与年龄相关。IgG1和IgG3在3岁左右接近成人水平，IgG2和IgG4在6岁之后接近成人水平。由于同种型限制，某些特异性抗体通常属于某一同种型（亚类）。亚类缺陷患者常反复感染。IgG2缺陷患者（常伴有IgA和IgG4缺陷）常发生上、下呼吸道反复感染，通常由化脓性微生物（嗜血杆菌、肺炎链球菌）引起。由于早期开始静脉注射免疫球蛋白替代疗法对长期预后有有益影响，早期诊断的重要性显而易见。
