Use of a very short protocol with no adjuvant in acute ovalbumin-sensitized allergic pulmonary response in mice for pre-clinical studies

Many limitations have been raised over the murine models with ovalbumin (OVA) sensitization in asthma research. However, this model is still widely used as a pre-clinical study for some new specific targets for treatment. The use of adjuvant and long sensitization periods are some of the limitations raised. We have tested whether a shorter period of subcutaneous sensitization with OVA, with no adjuvant, induces a similar eosinophilic pulmonary response in mice, when compared with previous well-established control protocols. Adult BALB/c mice were used and divided into groups, according to the number of OVA sensitizations (once or twice, OVA: 20 μg) and number (twice and 3x) and dosage (40 μg and 100 μg) of intranasal OVA challenge. The shorter protocol (10 days- length) consisted of one subcutaneous OVA sensitization and three OVA challenges (100 μg). Total and differential cell counts from bronchoalveolar lavage (BAL), eosinophil peroxidase (EPO) from lung tissue and histopathology (HE) of the lungs were performed 24 hours after the last OVA challenge. Cell counts from BAL, EPO from lung tissue and histological lung abnormalities were not different between the groups studied. The shorter protocol induced a significant eosinophilic lung response to OVA. We conclude that the use of one subcutaneous OVA sensitization elicit a strong allergic pulmonary response, free of adjuvant, and in a 10-day protocol. Our findings suggest that very short protocols with no adjuvant can be used as one of the pre-clinical tests for new drug investigations, reducing cost and time of experiments, and avoiding the use of artificial adjuvants during sensitization.