Resumo

Schistosomiasis is a serious parasitic disease directly related to poor socio-environmental conditions and achieves several Brazilian states. This is caused by the parasite Schistosoma mansoni, which has man as the definitive host. Asthma is a chronic disease of the airways and affects about 300 million people worldwide. This disease is the result of an exacerbated immune response against environmental allergens which occurs in atopic individuals. Some studies show that in places where there is high incidence of parasitic infections, allergic diseases are less frequent. The aim of our study was to evaluate the effect of immunization with different extracts of Schistosoma mansoni in the development of respiratory allergy in a murine model. BALB/c mice were divided into five groups. In the first three groups the animals received an intradermal S. mansoni female, male or both extracts three times with an interval of 15 days between each administration. The other groups were used as controls. In the allergy control control group the animals had only allergy induced by ovalbumin (OVA) and in the negative control group the animals were not induced allergy or were immunized with extracts of S. mansoni. After 15 days the animals were sensitized with OVA twice with an interval of seven days after the first sensitization. Seven days after the last sensitization, the animals were challenged intranasally with OVA. After 24 hours the animals were killed and bronchoalveolar lavage (BAL) was collected to determine the cellular profile involved in the inflammatory response and for the quantitation of IL-4, IL-5, IL-10 and IL-13. The right lung was collected for histopathologic evaluation of the local inflammatory response developed. As a result, it was observed that there is no significant difference in the total number of leukocytes and the level of production of the cytokines evaluated, although an increased number of neutrophils and eosinophils in animals that were immunized with extracts of male S. mansoni when compared to negative control group. Histopathology of the lung of the immunized animals showed that immunization does not lead to reduction in the inflammatory tissue. These results may indicate that modulation of the immune response not only dependent on the presence of antigen in the host organism but the stimulus induced by the presence of live parasites on the host organism.