MODULATION OF EXPERIMENTAL HYPERSENSITIVITY PNEUMONITIS BY SENDAI VIRUS

To evaluate the potential role of viruses in the pathogenesis or hyper sensitivity pneumonitis (HP), we looked at the effect of challenging n ormal versus Sendai-injected mice with Saccharopolyspora rectivirgula (SR). In this model of HP, mice are nasally instilled with SR antigen three consecutive days per week of study. For this study virus was giv en after 3 weeks of SR. Two positive (SR alone, virus alone) and a neg ative (saline) control groups were done in parallel with the viral plu s SR group. Lung response to these different conditions was evaluated by lung index, bronchoalveolar lavage (BAL) cell populations, lung his topathology, and BAL fluid fibronectin levels. SR challenge resulted i n an increase in BAL cells, lung index, and BAL fibronectin levels and in a peribronchial inflammatory reaction. The virus alone produced a transient increase in BAL cells. The cellular response to SR, in virus -injected animals, was greater than the added effects of the virus and SR. Virus alone had no persistent effect on the other measured parame ters and did not change the effect of SR on these variables. We conclu de that the Sendai virus enhances the cellular response of the mouse l ungs to an SR antigenic challenge.