The proposed research program is designed to study the nature of the lesions which nitrogen dioxide induces in the pulmonary cell populations involved in the immune response. The following topics will be investigated: 1. Compare the Effect of NO2 on the Viral and Nonviral Production of Interferon and Cytotoxic Activity by Lung Monocytes. Following exposure to NO2, the capacity of pulmonary cells lavaged from rabbits to produce interferon will be studied. The virus model will involve the use of Newcastle disease virus as the inducing agent and vesicular stomatitis as the challenge virus; poly I.poly C will be used as a nonviral inducer. 2. Determine the Effect of NO2 on the Mycobacterium Bovis (BCG)-Induced Cell Mediated Immune Response in the LUNG. The effect of NO2 on the quantity and functions of cells recruited into the lung following BCG vaccination will be examined. In particular, the generation of migration inhibitory factor (MIF), macrophage agglutinating factor (MAgF), cytotoxic activity, and immune interferon will be studied. 3. Determine the Effect of NO2 on Alveolar Macrophage Receptors Involved in the Immune Response. Experiments will be performed in vitro to study the effect of NO minus over 2 on inhibitory factor, interferon lymphocytes, immunoglobulin and complement.