目的：反复呼吸道感染（RRTI）是儿科的常见病之一。目前研究发现其发病与维生素A缺乏，免疫功能异常有关。该研究检测了RRTI患儿IgG 亚类及维生素A水平，并对该类病人维生素A缺乏与IgG亚类缺陷之间的关系进行了初步的探讨。方法：采用ELISA方法检测血清IgG 亚类；采用高效液相色谱分析Miller改良法进行维生素A的测定。结果：RRTI患者血清IgG2,4水平及维生素A水平均低于健康对照组，差异具有显著性（P<0.05）。结论：RRTI患者虽IgG正常，但是可能存在IgG亚类异常。RRTI患者存在维生素A水平低于正常儿童，而且IgG2,4水平的降低可能与维生素A水平有关。［中国当代儿科杂志，2007，9（6）：557-558］

OBJECTIVE: The development of recurrent respiratory tract infection (RRTI) is related to vitamin A deficiency and immune function abnormality in children. This study examined serum levels of IgG subclasses and vitamin A in children with recurrent respiratory tract infection.MethodsSerum IgG subclasses levels (IgG1, IgG2, IgG3, IgG4) were detected using ELISA and serum vitamin A levels were detected using high performance liquid chromatography-Miller method in 80 children with RRTI (ranged from 2-10 years old). The values were compared with those from 80 aged-matched healthy children.ResultsSerum levels of IgG2 (1.52±0.18 g/L) and IgG4 (0.22±0.12 g/L) in children with RRTI were significantly lower than controls (IgG2: 2.23±0.08 g/L; IgG4: 0.28±0.01 g/L) (P<0.05). Serum vitamin A levels in children with RRTI were also significantly lower than controls (1.16±0.22 μmol/L vs 1.56±0.12 μmol/L; P<0.05). IgG2 and IgG4 deficiency (27%) was the most common in 22 RRTI children with vitamin A deficiency.ConclusionsSerum levels of IgG subclasses, IgG2 and IgG4, and vitamin A decrease in children with RRTI. There might be some relationship between the decreased IgG2 and IgG4 levels and vitamin A deficiency. ［Chin J Contemp Pediatr, 2007, 9 (6):557-558］