Immune complexes and autoantibodies in silicosis

Serum specimens from 53 patients with silicosis were examined for the presence of antinuclear antibodies (ANA), rheumatoid factor (RF), immunoglobulins, and immune complexes. These humoral immunologic parameters were compared with radiographic changes and pulmonary function studies. A significant percentage of patients had an increased prevalence of ANA, RF, and immunoglobulin elevation (IgG, IgA). Immune complexes determined by the Raji-cell assay were detected in 31% of the patients. However, there was no significant correlation between any humoral immunologic abnormality and radiographic changes or declines in pulmonary function tests. These findings suggest that humoral immunologic abnormalities are not directly responsible for the lung changes in silicosis and cannot be used as "guides" to predict severity or progression of disease.