Inhibitory Effects of Amino-carbonyl Reactions Occurred between bovine beta-lactoglobulin and Lactose on the Oral Tolerance-inducing Activity of the Native Protein Antigen.

在本研究中，我们检测了是否口服耐受针对牛β-乳球蛋白，（β-Lg）是牛奶中最有效的过敏原之一，通过在60 ℃至90 ℃的应用温度范围内加热处理或不加热处理牛奶10-300分钟来诱导。（3 -Lg，在用β-Lg免疫前2-62天，每天口服约3 mI/头的牛奶或加热牛奶，然后通过测量^3H-胸苷摄取（T细胞增殖试验）检测淋巴结细胞的体外抗原特异性增殖反应，并通过一种酶-免疫吸附试验（ELISA）。通常发现，与对照小鼠相比，喂食生牛奶8天，针对β-Lg的抗体和T细胞应答水平均降低至1/10以下，并且即使在较长时间喂食牛奶后，无应答状态也几乎保持不变。但热牛奶不能很好地诱导小鼠的口服耐受。这种耐受性的抑制作用随着温度、时间和喂养时间的增加而逐渐增强。将5组小鼠分别口服给予PBS（对照）、β-Lg、β-Lg加乳糖、加热的β-Lg和加热的β-Lg加乳糖，并比较在各组小鼠中观察到的免疫耐受的程度。仅在给予加热的β-Lg加乳糖的组中显示出对β-Lg和加热的β-Lg加乳糖两者特异性的口服耐受性的显著抑制，这表明β- Lg和乳糖之间发生的氨基-羰基（美拉德）反应可能降低天然蛋白抗原的口服耐受性诱导活性。

In the present study, we examined whether oral tolerance directed against bovine beta- lactoglobulin (beta -Lg), one of the most potent allergens in cow's milk, was induced by feeding of cow's milk with or without heat treatments at the applied temperature ranging from 60ﾟC to 90 ﾟC for a period of 10-300 min. Groups of female C3H/HeN mice, a higher responder to (3 -Lg, were orally given with about 3 mI/day/head of the milk or heated milk during 2-62 days prior to the immunization with beta-Lg. The lymph node cells were then tested for their in vitro antigen-specific proliferative response by measuring ^3H-thymidine uptake (T cell proliferation assay) and their sera were also investigated for the binding to beta -Lg by an enzyme-linked immunosorbent assay (ELISA). The feeding of raw milk for 8 days was usually found to lower the both levels of antibody and T cell responses against beta-Lg to less than 1/10 as compared with the control mice, and the unresponsiveness state was held almost constant even after the longer feeding of the milk. The oral tolerance, however, could not be well induced by feeding of the heated milk. Such inhibition of the tolerance was gradually enhanced with increasing the applied temperature, time and the feeding period.Next, we studied why the poor tolerance was induced by feeding with the heated milk in mice. Five groups of mice were orally administrated with PBS (control), beta-Lg, beta-Lg plus lactose, heated beta-Lg and heated beta-Lg plus lactose, respectively, and compared the magnitude of immunological tolerance observed in each group of mice. The significant inhibition of oral tolerance specific for both beta-Lg and heated beta-Lg plus lactose was shown in only the group given with heated beta-Lg plus lactose, suggesting that amino-carbonyl (Maillard) reactions occurred between beta- Lg and lactose may lower the oral tolerance-inducing activity of the native protein antigen.