Abstract:

Objective To observe whether lactalbumin hydrolysate can induce oral tolerance, and explore the relationship between Th2 related cytokines and oral tolerance to food. Methods BALB/c mice (n=176) were fed with lactalbumin and its hydrolysate, the models of oral tolerance were established, and control group A, lactalbumin group, partially hydrolysed lactalbumin group and extensively hydrolysed lactalbumin group (n=44) were divided. Meanwhile, BALB/c mice (n=83) were allergized and stimulated by lactalbumin to establish the models of food allergy, and control group B (n=41) and lactalbumin allergy group (n=42) were divided. The serum levels of IgE, IgG, IgG1, IL-4 and TGF-β1 were detected by ELISA, the pathological features of intestines were analysed, and the percentages of CD4+CD25+Foxp3+Treg in splenic cells were determined by flow cytometry. Results Compared with control group A, the serum levels of IgE, IgG1, IgG and IL-4 in lactalbumin group were lower, while the serum level of TGF-β1 was higher, and the percentage of CD4+CD25+Foxp3+Treg in splenic cells was higher (P<0.05). The serum levels of IgE and IL-4 were lower in partially hydrolysed lactalbumin group, while the serum level of TGF-β1 was higher, and the percentage of CD4+CD25+Foxp3+Treg in splenic cells was higher (P<0.05). There was no significant difference in each parameter between extensively hydrolysed lactalbumin group and control group A (P>0.05). Compared with control group B, the serum levels of IgE and IL-4 in lactalbumin allergy group were higher, while the serum level of TGF-β1 was lower, and the percentage of CD4+CD25+Foxp3+Treg in splenic cell was higher (P<0.05). Conclusion Both lactalbumin and partially hydrolysed lactalbumin may induce oral tolerance with main feature of suppression of Th2 lymphocyte responses, while extensively hydrolysed lactalbumin may induce no significant reaction.

Key words: oral tolerance, milk allergy, lactalbumin, IgE