Carbonare S B, Silva M L, Palmeira P, Carneiro-Sampaio M M
Instituto Butantan, Universidade de São Paulo, Brazil.
J Diarrhoeal Dis Res. 1997 Jun;15(2):53-8.
IgA antibodies reacting to enteropathogenic Escherichia coli (EPEC) antigens in human colostrum and their role in the inhibition of EPEC adherence to HEp-2 cells were studied. Colostrum IgA was isolated with a Sepharose anti-IgA column. IgA-depleted colostrum lost its inhibitory effect on EPEC adhesion, while the IgA-enriched eluate was a potent adherence inhibitor. The same eluate showed a significant loss of inhibitory activity after absorption with an EPEC strain showing localised adherence (LA+), but no alteration after absorption with an LA- strain. No bands were observed in Western blot analysis with LA+ absorbed eluate and with a crude extract of the EPEC strain, but the eluate absorbed with LA- showed a strong recognition of a 94-kDa band, a molecular weight equivalent to that of intimin. Colostrum antibodies reacting to non-protein antigens were not detected by Western blot analysis. The persistence of anti-EPEC IgA in the gastrointestinal tract was shown by the strong reactivity to the 94-kDa band in Western blot analysis of one mother's colostrum and her infant's faeces. These data confirm the role of colostrum antibodies in protecting the neonate against infections due to EPEC.
研究了人初乳中与肠致病性大肠杆菌（EPEC）抗原反应的IgA抗体及其在抑制EPEC黏附于HEp-2细胞中的作用。用琼脂糖抗IgA柱分离初乳IgA。去除IgA的初乳失去了对EPEC黏附的抑制作用，而富含IgA的洗脱液是一种有效的黏附抑制剂。同一洗脱液在用表现为局部黏附（LA+）的EPEC菌株吸收后，抑制活性显著丧失，但在用LA-菌株吸收后无变化。用LA+吸收的洗脱液和EPEC菌株的粗提物进行蛋白质印迹分析时未观察到条带，但用LA-吸收的洗脱液显示出对一条94 kDa条带的强烈识别，该分子量与紧密黏附素相当。蛋白质印迹分析未检测到与非蛋白质抗原反应的初乳抗体。通过对一位母亲的初乳及其婴儿粪便进行蛋白质印迹分析，对94 kDa条带的强反应性表明了抗EPEC IgA在胃肠道中的持久性。这些数据证实了初乳抗体在保护新生儿免受EPEC感染方面的作用。
