Background: Several lung diseases are characterized by a predominantly neutrophilic inflammation. A better understanding of the mechanisms of action of some drugs on the airway inflammation of such diseases may bring advances to the treatment. Objective: To develop a method to induce pulmonary neutrophilic response in mice, without active infection. Methods: Eight adult Swiss mice were used. The study group (n = 4) received an intranasal challenge with 1 x 1012 CFU/ml of Pseudomonas aeruginosa (Psa), frozen to death. The control group (n = 4) received an intranasal challenge with saline solution. Two days after the intranasal challenge, a bronchoalveolar lavage (BAL) was performed with total cell and differential cellularity counts. Results: The total cell count was significantly higher in the group with Psa, as compared to the control group (median of 1.17 x 106 and 0.08 x 106, respectively, p = 0.029). In addition to this, an absolute predominance of neutrophils was found in the differential cellularity of the mice that had received the Psa challenge. Conclusion: The model of inducing a neutrophilic pulmonary disease using frost-dead bacteria was successfully developed. This neutrophilic inflammatory response induction model in Swiss mice lungs may be an important tool for testing the anti-inflammatory effect of some antimicrobial drugs on the inflammation of the lower airways.

Keywords: Animal experimentation. Lung disesases. Inflammation. Neutrophils. Pseudomonas.