Efeito de uma dieta livre de proteínas no desenvolvimento de alergia alimentar e tolerância oral em camundongos BALB/c

Abstract

In this study, we investigated the role of administrating a protein-free diet in the induction of food allergy and oral tolerance in BALB/c mice. The experimental model used was mice fed, since weaning up to adulthood, a balanced diet in which all proteins where replaced by amino acids (Aa diet). As previously described by our group in C57BL/6 mice, BALB/c mice fed Aa diet had an immature immune system that was similar to the one found in neonates and germ-free mice. Protein absence in the diet did not prevent the development of food allergy to ovalbumin (OVA) in these animals. However, Aa-fed mice produced lower levels of IgE, secretory IgA, cytokines (IL-4, IL-5, IL-10 e IFN-), higher consumption of OVA-containing during the period of food allergy induction. In addition, when compared to mice from control group, Aa-fed mice had lower weight loss related to the aversion phenomenon during food allergy. Immature mice that did not have protein in their diets could be rendered tolerant but they were less susceptible to oral tolerance induction. One single gavage was not enough to suppress specific Ig and IgG1 in the Aa-fed group although it was efficient to induce suppression for the control group of mice. Our results indicate that the absence of protein in the diet alters both inflammatory and regulatory immune reactivity in mice probably due to the immature status that they induce.