Specificity and duration of post-inflammatory suppression in rabbit lungs challenged with aerosolized antigen.

Rabbits immunized and aerosolized with soluble protein antigens develop a short lived pulmonary inflammation. This is followed by a period of non-specific unresponsiveness which lasts approximately 30 weeks after the first exposure to aerosol treatment. This period is characterized by the inability of the rabbit to exhibit another inflammatory reaction either to the same antigen used to induce the first inflammation, or to a new antigenically unrelated antigen. After 30 weeks however, the animals become responsive (develop another pulmonary inflammation) to a second unrelated antigen, but remain unresponsive to the antigen used to elicit the initial inflammatory response. These studies indicate that following challenge with inhaled antigen, rabbits develop a non-specific suppression of pulmonary inflammation which lasts a finite period of time. When this disappears, the animal is left with an antigen specific suppression of pulmonary inflammation. These studies suggest a model for normal individuals who may respond similarly to potentially harmful inhaled allergens. Individuals with hypersensitivity pneumonitis, however, may not develop antigen specific unresponsiveness. The nature of this unresponsiveness is unknown at present, nor is it known when it begins to develop.