Parainfluenza-3 induced hyperreactivity of the guinea pig trachea coincides with an increased number of bronchoalveolar cells.

Guinea pigs were inoculated intra-tracheally with bovine parainfluenza type 3 virus (PI-3) to investigate whether airway hyperreactivity was associated with an increase in the number of broncho-alveolar cells. Two days after saline or PI-3 inoculation no difference in histamine reactivity of the isolated tracheal spirals was observed. The number of broncho-alveolar cells was also not changed. However, 4 days after PI-3 inoculation the histamine-induced contraction of the tracheal spirals was increased by 45% and the number of inflammatory cells in the airways by 150% as compared with the control group. In conclusion, PI-3 infection of the guinea pig respiratory airways induces tracheal hyperreactivity which is associated with an increase in broncho-alveolar cells.