Analysis of rabbit lung lavage immunoglobulins during the course of pulmonary inflammation induced with aerosolized antigen

Lung lavage fluids (LLF) from rabbits with pigeon dropping extract (PDE)-induced granulomatous pulmonary inflammation were studied for protein and immunoglobulin (Ig) G and A levels. It was found that the protein levels of the lung fluids of rabbits increased to a maximum after 2-3 weeks of aerosol treatment with PDE during which time inflammation of the lung increases. This is followed by a gradual decrease in protein content as the inflammation wanes and the lung returns to normal. These variations primarily reflect changes in IgG and IgA levels. IgG and IgA levels follow different courses. IgA reaches a maximum in the first week of inflammation and then gradually decreases. In contrast, IgG reaches a maximum level (2-3 weeks) and stays at an elevated level throughout the 12 week period of aerosol treatment with PDE. Antibodies to PDE in these two classes of immunoglobulins do not entirely reflect the immunoglobulin class levels. IgA antibody levels reach a maximum after extended aerosol challenge while IgG antibody reaches a maximum early and then declines to background levels. The specificity of the non-PDE antibody IgG is unknown at present. The distribution of IgA subclass producing cells in the lung is different than in the gut. In the lung the major subclass is g while in the gut it is f. The distribution of subclasses of IgA in the LLF, however, does not appear to reflect the cellular distribution. The reason for this is not clear.