The protein coating of asbestos bodies.

1. Asbestos bodies were isolated from human lungs and the amino acid composition of the protein content was determined. 2. The hydroxyproline, glycine, leucine and phenylalanine values indicate that the protein in the coating cannot be principally collagen. 3. Albumin can be adsorbed on chrysotile asbestos as a monolayer but more than a monolayer is adsorbed if iron is also adsorbed. 4. Ferritin is adsorbed on chrysotile to give a thick layer. 5. The amino acid composition and adsorption studies are discussed in the light of the suggestions that the protein coating of asbestos is collagen (Beattie, 1961) or ferritin (Davis, 1964).