Orosomucoid, alpha 2-macroglobulin and immunoglobulins in serum and pleural effusions

Serum and pleural fluid levels of orosomucoid, alpha 2-macroglobulin, IgG, IgA, and IgM were measured in 36, 29, and nine patients suffering from malignant, tuberculous, and non-malignant, non-inflammatory pleural disease, respectively. Pleural fluid concentrations of the studied proteins were higher in tuberculous effusions, but due to wide overlapping of the values, correlation with diagnosis could not be established. The ratio of the pleural fluid to the serum concentration of the studied proteins was below unity with the exception of three tuberculous and one cancer patient who showed higher values of orosomucoid in the pleural fluid. The rate of diffusion of the various proteins in the pleural fluid was inversely proportional to their molecular weight.