卵清蛋白致敏小鼠肠道黏膜sIgA抗体反应的实验研究

Experimental study on the intestinal mucosal secretary IgA responses to the ovalbumin-induced allergy in mice

目的探讨卵清蛋白(OVA)胃肠致敏时,BALB/c小鼠肠黏膜分泌性免疫球蛋白A(sIgA)抗体反应系统特点,以期为临床食物过敏的诊断和治疗提供一定依据。方法选用6周龄无鸡蛋蛋白饲养的BALB/c雌鼠为实验对象,分为激发(Ch)组及正常生理盐水对照(NS)组,每组8只。ELISA法测定小鼠小肠黏液中总IgA、OVA特异性IgA含量;免疫组织化学法检测小鼠小肠固有层(LP)IgA+浆细胞,集合淋巴小结中膜表面IgA+(smIgA+)淋巴细胞数量;RT-PCR法检测小鼠小肠组织白介素4(IL-4)mRNA表达;组织原位杂交法检测小鼠小肠集合淋巴小结(PP)中IL-4的mRNA表达。结果Ch组小鼠肠道黏液中总IgA、OVA特异性IgA、肠道固有层IgA+浆细胞、PP中smIgA+淋巴细胞均较NS组升高(P均<0·01),各指标间存在正相关(P均<0·01),Ch组小鼠小肠LP及PP中IL-4mRNA表达高于NS组(P均<0·01),小鼠小肠LP与PP内IL-4mRNA表达分别与LP内IgA+浆细胞、PP内smIgA+淋巴细胞数量呈正相关(P均<0·01)。结论OVA致敏小鼠肠黏膜sIgA抗体系统存在功能亢进现象,其原因可能与炎症状态下肠道黏膜诱导部位和效应部位IL-4转录异常增高有关。

Objective To valuate the intestinal mucosal secretary IgA （sIgA） responses to the ovalbumin-induced allergy in mice, to provide some clues for the exploration of mechanisms and therapeutic methods in the children＇s food allergy. Methods Female BALB/c mice aged 6 weeks fed on the ovalbulminfree diet, were randomly divided into 2 groups with 8 mice in each. The mice in group Ch were sensitized with ovalbumin （OVA） intraperitoneal injection two times and challenged intragastrically 3 times. Two days after the last challenge with oral OVA, the mice were sacrificed and the samples were collected. The mice in group Ns were given intraperitoneal and intragastrical normal saline as control The levels of total IgA and OVA-specific IgA in the intestinal mucus of the mice were determined by ELISA; the immunohistochemical methods were adopted to observe IgA^＋ plasmacytes in lamina prepria （LP） and surface membrane IgA （smIgA）^＋ lymphocytes in peyer＇s patch （PP） ;the IL-4 mRNA expression in LP was assessed by RT-PCR. The IL-4 mRNA expression in PP was evaluated by in situ hybridization. Results After the mice in Call group were sensitized and challenged with OVA, the levels of the total IgA and the OVA-specific IgA in mucus remarkably increased （P 〈0. 01 respectively）, the amounts of the IgA ＋ plasmacytes in LP and the smIgA^＋ lymphocytes in PP significantly increased （P 〈 0. 01 respectively ）; a significantly positive correlation was found among the total IgA levels, the OVA-specific IgA levels, the IgA^＋ plasmacyte counts in LP and the smIgA^＋ lymphocyte counts in PP （P 〈0. 01 respectively） ; the mRNA expressions of IL-4 in LP and in PP were significantly augmented （P 〈0.01 respectively） ; significantly positive correlations were found either between the IL-4 mRNA expression and the IgA^＋ plasmacyte counts in LP （P 〈 0. 01） or between the IL-4 mRNA expression and the smIgA^＋ lymphocyte counts in PP （P 〈0.01 ）. Conclusions The intestinal mucosal sIgA responses are abnormally augmented in the ovalbumine-induced allergic mice, which may be partly due to the increased expression of IL-4 mRNA in gut.