Novo modelo experimental de alergia alimentar à proteína do leite -Lactoglobulina em camundongos

Abstract

Food allergy is an abnormal immune response against dietary antigens and its incidence has increased in developed and developing countries. It is known that cows milk allergy is very common. About 2.5% of children are affected in their first year of life. Several models of allergy to cows milk allergy have been already described. Usually they focus in one of its major immunogenic components: the -lactoglobulin protein (BLG). These models usually require either a long time to be performed, the use of choleric toxin or intense manipulation of animals. Herein, we report a novel model of food allergy to BLG using an easy and rapid protocol. BALB/c mice were intraperitoneally sensibilized with antigen adsorbed into aluminum hidroxide and, 14 days later, they received a second sensibilization, with the antigen in saline solution. One week thereafter, animals were orally challenged with a BLG-contatining solution. Oral challenged were tested for two periods of time: either 7 or 14 days. We observed that sensibilized and orally challanged animals showed high levels of antigen specific IgE at both periods of time. In addition, mice presented weight loss and reduction in adipose tissue. Food allergy generates a classical phenomenon known as aversion, in which animals reject to ingest the antigen to which they were sensitized to. Indeed, allergic mice avoid drinking a BLG-containing solution at a certain extent. However, in a preference test when animals could choose between consuming either a solution containing the allergen or a control solution, both non-allergic and allergic mice choose to drink the BLG-containing solution. We also measured some histological parameters and observed an increase in eosinophils and intra-epithelial lymphocytes in the proximal jejunum. Mucus production was not affected in this model. Levels of secretory IgA were elevated in allergic 14-day-challenged animals when compared to their controls. Levels of IL-4 were increased in mesenteric lymph nodes and proximal jejunum whereas levels of TGF-beta were increased and of IL-10 were decreased in the proximal jejunum of allergic mice. Therefore, we have described a novel model of allergy to cow´s milk that may represent a useful in future studies on very prevalent type of food allergy.