Deo Sudha S, Vaidya Avinash K
Immunology Department, Bai Jerbai Wadia Hospital For Children, and Child Health Research Society, Parel, Mumbai, India.
Indian J Pediatr. 2004 Jan;71(1):37-40. doi: 10.1007/BF02725654.
Urinary secretory IgA (sIgA), an immunoglobulin synthesized locally in mucosal surface is an important immunological defense in preventing bacterial adherence to periurethral epithelia and uroepithelia. Therefore attempts were made to measure secretory IgA in the urine of children with urinary tract infections (UTI), by using sIgA specific ELISA.
Fresh or unprocessed urine samples from healthy donors (children and adults N=10 each), 68 children and 17 Adults with UTI were tested for the presence of sIgA.
The level of sIgA in 10 healthy normal children was 2.7 +/- 0.94 ug/ml and that in 10 healthy adults was 5.2 +/- 0.73 ug/ml. Children with UTI showed highly elevated levels of sIgA amounting to 279 +/- 80 ug/ml (p<0.001). It was interesting to note that 96% of children and 76% of adults with UTI had sIgA level significantly above that of +/- 2SD of respective controls (287 +/- 99 and 80 +/- 48 ug/ml respectively). On culturing the urine obtained from these children the colonies identified were E. coil about 46%, Klebsiella about 24% and Pseudomonas about 24%. The sIgA antibody from urine samples assessed by indirect immunoflourescense. specifically reacted with the respective organism.
Taken together the results show that the presence of sIgA not only correlated with the UTI in children as well in adults but sIgA seems to be directed to the infective agent and can also be used to identify the type of infection. Thus measurement of urine antibody levels may provide an alternative marker of host responses to infection, which can be used either as a simple screening test or could be useful to assist alongwith other tests in establishing a diagnosis.
尿分泌型IgA（sIgA）是在黏膜表面局部合成的一种免疫球蛋白，是防止细菌黏附于尿道周围上皮和尿路上皮的重要免疫防御物质。因此，本研究尝试采用sIgA特异性酶联免疫吸附测定法（ELISA）检测尿路感染（UTI）患儿尿液中的分泌型IgA。
对来自健康供者（儿童和成人各10例）、68例UTI患儿及17例UTI成人的新鲜或未经处理的尿液样本进行sIgA检测。
10例健康正常儿童的sIgA水平为2.7±0.94μg/ml，10例健康成人的sIgA水平为5.2±0.73μg/ml。UTI患儿的sIgA水平显著升高，达279±80μg/ml（p<0.001）。值得注意的是，96%的UTI患儿和76%的UTI成人的sIgA水平显著高于各自对照组±2SD水平（分别为287±99和80±48μg/ml）。对这些患儿的尿液进行培养，鉴定出的菌落中大肠杆菌约占46%，克雷伯菌约占24%，假单胞菌约占24%。通过间接免疫荧光法评估尿液样本中的sIgA抗体，其与相应病原体发生特异性反应。
综合结果表明，sIgA的存在不仅与儿童及成人的UTI相关，而且sIgA似乎针对感染病原体，还可用于识别感染类型。因此，检测尿液抗体水平可能提供宿主对感染反应的另一种标志物，可作为一种简单的筛查试验，或有助于与其他检查一起用于确诊。
