| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1998: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Research Abstract |
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.
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