Absorption of serum proteins by inorganic dusts.

287-292. Four samples of coal dust of different ranks, five types of asbestos, and a sample of silica were each incubated with normal serum and with IgG and the amount of protein absorbed onto the particle surfaces was estimated. The total amount of protein absorbed by the coal samples was not related to the rank of coal, and surface absorption by the dusts did not detectably alter protein to a form capable of reacting with rheumatoid factor, the latter finding being in disagreement with the hypothesis put forward by Payne (1963) to explain the presence of rheumatoid factor in the serum of a large proportion of coal workers with pneumoconiosis. Estimation of immunoglobulin levels after incubation of normal serum with 10 samples of coal suggested that IgG might be selectively absorbed, and RF was absorbed in preference to normal serum proteins by dust samples which had not been coated with normal serum.